VATICAN CITY (REUTERS, AFP) - Pope Benedict, speaking in his last Sunday address before his resignation, said he was following God's wishes, and that he was not abandoning the Roman Catholic Church.

The Pope, addressing tens of thousands of people at St Peter's Square with a strong voice, also said he would continue to serve and love the Church by praying and meditating after his historic abdication on Thursday. He said God had called him "to climb the mountain".

"The Lord is calling me to climb onto the mountain, to dedicate myself even more to prayer and meditation," he said to cheers of "Long Live the Pope!".

"But this does not mean abandoning the Church. Actually, if God asks this of me, it is precisely because I can continue to serve her with the same dedication and the same love I have shown so far," he said.

However, he said he would be serving the Church "in a way more in keeping with my age and my forces".

The Sunday address was one of Benedict's last appearances as Pontiff. On Wednesday, he will hold his last general audience at St Peter's Square and on Thursday he will meet with cardinals and then fly to the papal summer retreat south of Rome.

The papacy will become vacant at 8pm Rome time on Thursday (3am Singapore time on Friday). Cardinals will begin meetings the next day to prepare for a conclave, likely to start in mid-March, where they will elect a new pope from among themselves.

Benedict's shock resignation ended an eight-year pontificate dominated by the priest child sex abuse scandal and efforts to counter rising secularism in the West.

The Vatican and Rome police estimated the numbers at more than 100,000 people - many times more than usually attend the traditional Sunday prayer.

Benedict will be only the second pope to resign of his own free will in the Church's 2,000-year history, and the first to do so since the Middle Ages.