Federal NDP leader Jack Layton has announced he is taking an indefinite medical leave from the leadership of the party, after being diagnosed with a second type of cancer.

Appearing thin and tired at a news conference in Ottawa Monday, Layton said treatment has continued to be successful for prostate cancer, which was diagnosed in 2010.

He continued treatment until this year's election that saw him elevated to leader of the official opposition. Layton did not disclose what other kind of cancer has been detected, but vowed to recover and return to lead the party when the House of Commons resumes sitting in September.

Layton recommended Hull-Aylmer MP Nycole Turmel, one of a surge of new Quebec MPs that lifted the NDP to 103 seats. Layton, leader since 2003, was the focus of the campaign that saw a collapse of Liberal and Bloc Quebecois support.