Pope Benedict XVI made his first public appearance on Wednesday since his resignation announcement, asking thousands of cheering pilgrims at the Vatican to "keep praying for me".

Pope Benedict XVI made his first public appearance on Wednesday since his resignation announcement, asking thousands of cheering pilgrims at the Vatican to "keep praying for me".

The 85-year-old pontiff was greeted by a standing ovation and chants of "Benedetto", his name in Italian, at his weekly audience, with a prominent banner reading "Thank You, Holiness".

The pontiff -- the first to resign voluntarily in 700 years -- said he had made his momentous decision "for the good of the Church".

Vatican spokesman Federico Lombardi announced that cardinal electors will meet in mid-March to choose Benedict's successor.

"The beginning of the conclave cannot be before March 15," Lombardi told the Vatican press corps. "We have to expect a conclave starting on the 15th, 16th, 17th 18th or 19th."

The secret conclave held in the Sistine Chapel under Michelangelo's famed ceiling frescoes -- deliberations that normally last a few days -- should produce a new pope in time for Easter.

As rumours fly over front-runners, commentators have said age may be a key factor in selecting a new pope, with 117 cardinals eligible to vote for one of their peers.