NEW YORK – The NFL is going deeper into the wallets of players who get caught using steroids and other performance-enhancing drugs.

After four months of sometimes intense negotiations, the league and union announced Wednesday more extensive testing for performance-enhancing drugs and the addition of the blood-boosting substance EPO to its list of banned substances.

The union also agreed that players suspended after testing positive will, for the first time, forfeit a portion of their signing bonuses in addition to the salary they will lose during their time away. That is significant because the signing bonuses often are the only guaranteed portion of a player’s salary and can be larger than salaries, which sometimes are kept artificially low to keep the team under the salary cap.

“It is important that the NFL and its players continue to be leaders on the issue of illegal and dangerous performance-enhancing drugs in sports,” NFL commissioner Roger Goodell said.

The agreement also increases from seven to 10 of the number of players on each team randomly tested each week during the season for steroids and other performance-enhancing drugs. That means there will be 12,000 tests each season, up from the current 10,000.