TORONTO -- Jack Layton says he has been diagnosed with another form of cancer and is taking a leave of absence as leader of the federal New Democrats to fight it.

The 61-year-old politician announced he was battling prostate cancer in February 2010.

But he says recent tests show he has a new form of cancer and he requires further treatment.

Appearing at a news conference in Toronto with his wife Olivia Chow, Layton appeared to have lost weight and sounded weak.

He underwent hip surgery in early March, just weeks before the start of the federal election campaign.

Layton maintained a rigorous schedule throughout the campaign despite frequent questions about his health.

The NDP went on to score more seats than ever and capture official Opposition status for the first time in its 50-year history.