New York City ? A failed plot to set off bombs in the New York subway system last year was part of a larger al-Qaida terrorist conspiracy that included a similar attack planned in England, U.S. prosecutors said Wednesday.

In an indictment unsealed Wednesday in federal court in Brooklyn, prosecutors added several al-Qaida figures to the case, including Adnan Shukrijumah, an FBI most-wanted terrorist.

Shukrijumah, one of the al-Qaida leaders in charge of plotting attacks worldwide, was directly involved in recruiting and plotting the New York attack, prosecutors said. Attorney General Eric Holder has called that plot one of the most dangerous since the Sept. 11, 2001, attacks.