The Archbishop of Cologne, Cardinal Rainer Maria Woelki, has offered his resignation to Pope Francis over his handling of allegations of child sex abuse committed by priests.

An 800-page report into the abuse cases in the archdiocese between 1975 and 2018 found more than 200 abusers and more than 300 victims mostly under the age of 14.

Woelki had taken a break from his duties as head of the largest diocese in the world's richest Catholic Church in September due to the criticism over the scandal. The pope has yet to comment on whether he to will accept the resignation.

"I placed my service and office as Archbishop of Cologne at the Holy Father's disposal, so that he is free to decide what best serves the Church of Cologne," he wrote in a letter to his congregation.

The pope dispatched two senior foreign bishops in May to investigate the archbishop's handling of the allegations, in particular for shelving a report into wrongdoing by priests over unspecified shortcomings in methodology.

The Vatican found no evidence Woelki had broken the law, but said he had made "grave errors".

Shortly afterwards the Pope allowed Woelki to depart for a 30-day break of "meditation" and "spiritual exercise".

The affair caused convulsions in Germany's 20 million-strong Catholic flock, triggering a rush to leave the church to the extent that authorities ran out of time slots to accommodate all the people who wanted to make a formal declaration of departure.

Germany's Church has an outsize influence on the global Catholic Church since it is funded by church taxes collected by the state from its members, making it the world's wealthiest.