BERLIN-Three suspected Islamic terrorists from an al-Qaida-influenced group nursing “profound hatred of U.S. citizens” were arrested on suspicious of plotting imminent, massive bomb attacks on U.S. facilities in Germany, prosecutors said Wednesday.

A senior State Department official said German investigators had determined the Frankfurt International Airport and the nearby U.S. Ramstein Air Base were the primary targets of the plot but that those arrested may have also been considering strikes on other sites, particularly facilities associated with the United States.

It was the second time in as many days that European officials said they had thwarted a major attack, following the arrest by Danish authorities on Tuesday of eight alleged Islamic militants with links to senior al-Qaida terrorists. It also comes less than a week before the sixth anniversary of the Sept. 11 attacks on the United States.

German Federal Prosecutor Monika Harms said the three suspects, two of whom were German converts to Islam, had trained at camps in Pakistan run by the Islamic Jihad Union, a group based in Central Asia. They had obtained some 1,500 pounds of hydrogen peroxide for making explosives.

“We were able to succeed in recognizing and preventing the most serious and massive bombings,” Harms told reporters. She declined to name specific targets, but said the suspects had an eye on institutions and establishments frequented by Americans in Germany, including discos, pubs and airports.

The senior State Department official, speaking on condition of anonymity to describe discussions between American and German intelligence agencies, said the threat had been a major reason the U.S. Embassy in Berlin had boosted security and issued two warnings in April and May about possible impending terrorist attacks.

Chancellor Angela Merkel called the arrests a “very, very great success.”

“This shows that terrorist dangers, in our country as well, are not abstract but are real,” she said. “It also shows for me that international cooperation is of decisive significance in the fight against terrorism.”

Deputy State Department spokesman Tom Casey welcomed the arrests. “We’re very pleased that the government of Germany has taken this action,” he said. “It represents their strong cooperation with us and their strong commitment to fighting the war on terror.”

Casey declined to discuss the potential targets but said “our general understanding was that these individuals were looking at the possibility of attacking a number of locations, including some prominent public sites as well of some of those specifically associated with American interests or the American government.”

The suspects, delivered by helicopter, made a first appearance at a closed hearing at the Federal Court of Justice in Karlsruhe, which ordered them held pending trial.

Officials said the solution of hydrogen peroxide, stored in a hide-out, could have been mixed easily with other additives to produce a bomb with the explosive power of 1,200 pounds of TNT.

“This would have enabled them to make bombs with more explosive power than the ones used in the London and Madrid bombings,” Joerg Ziercke, the head of the Federal Crime Office – Germany’s equivalent of the FBI – said at a joint news conference with Harms.

The three suspects- two Germans aged 22 and 28, and a 29-year-old Turk – first came to the attention of authorities because they had been caught observing a U.S. military facility in Hanau, near Frankfurt, at the end of 2006, officials said.

All three had undergone training at camps in Pakistan run by the Islamic Jihad Union, and had formed a German cell of the group, which officials said was influenced by al-Qaida.

The Islamic Jihad Union was described as a Sunni Muslim group based in Central Asia that was an offshoot of the Islamic Movement of Uzbekistan, an extremist group with origins in that country.

“The group, which is influenced by al-Qaida, set up a German cell in winter of 2006 with the goal of finding recruits here to carry out attacks,” Harms said.

The three had no steady work and were drawing unemployment benefits while their main occupation was the plot, officials said. “This group distinguishes itself through its profound hatred of U.S. citizens,” Ziercke said.

Members of Germany’s elite GSG-9 anti-terrorist unit arrested two suspects at a vacation home in central Germany on Tuesday, Ziercke said. A third managed to escape through a bathroom window, but was apprehended about 300 yards away by federal police who had roped off the area.

Gordon Johndroe, spokesman for the National Security Council, said President Bush had been briefed on the arrests and that he was “pleased a potential attack was thwarted and appreciates the work of the German authorities and the cooperation by international law enforcement.”

Germany, which did not send troops to Iraq, has been spared terrorist attacks such as the mass transit bombings in Madrid and London – although its involvement in the attempt to stabilize Afghanistan has led to fears it might be targeted.

German and U.S. officials have warned of the possibility of a terrorist attack, and security measures have been increased.

In July 2006, two gas bombs were placed on commuter trains but did not explode. Officials said that attack was motivated by anger over cartoons portraying the Prophet Muhammad in a Danish newspaper. Several suspects are on trial in Lebanon, and a Lebanese man has been charged in Germany.

Wolfgang Bosbach, a top legislator for Merkel’s Christian Democrats, pointed out next week’s anniversary of the Sept. 11 terrorist attacks, as well as upcoming deliberations by the German parliament over whether to extend its troop mandates in Afghanistan.

“We are in a highly sensitive period,” he said.

Merkel said in an interview released Wednesday that German troops would remain in Afghanistan for several more years, despite recent setbacks in the region.

Ramstein is one of the best-known U.S. Air Force bases worldwide because it serves as a major conduit for U.S. troops moving in and out of Europe, Asia and the Middle East. It is a key transit point for injured troops from Iraq and Afghanistan who are flown there en route to a U.S. medical hospital at nearby Landstuhl.

FBI spokesman Richard Kolko said the FBI and Department of Homeland Security were “monitoring the situation in Germany but “see no imminent threat to the U.S. domestically following these arrests.”

Ziercke said that although there were similarities to the group arrested in Denmark on Tuesday, no direct connection between the two had been established.

The European Union’s top justice official said Wednesday that the threat of a terror attack remained high in the 27-nation bloc. EU Justice and Home Affairs Commissioner Franco Frattini said the EU executive would push ahead with plans to set up an EU-wide airline passenger data recording system despite privacy concerns.