A German comedian prosecuted for reciting an obscene poem about President Recep Tayyip Erdogan live on television said German Chancellor Angela Merkel "filleted" him and served him for tea to the Turkish leader.

In March, Erdogan filed criminal charges against comedian Jans Boehmermann after he read out the poem.

The Turkish government demanded that German authorities prosecute Boehmermann under obscure German legislation, banning insults against foreign heads of state, and in April Merkel approved the request.

Breaking his silence, Boehmermann criticised Merkel, who is currently involved in delicate negotiations with Turkey to reduce the number of refugees entering Europe.

"The Chancellor must not wobble when it's a matter of freedom of opinion," Boehmermann told Die Zeit. "But instead, she filleted me, (and) served me for tea to a highly strung despot and made me into a German Ai Weiwei."

Erdogan has sued thousands of people accused of insulting him since becoming president in 2014. After Boehmermann's poem was broadcast, Merkel told Turkish President Ahmet Davutoğlu that the poem was "deliberately offensive".

She was criticised for buckling to Turkish pressure and subsequently admitted to regretting making the comment.

When announcing that the prosecution against Boehmermann would be allowed to proceed, she said the law banning insults against foreign heads of state would be revised.

German investigators in Mainz, who are handling the criminal complaint against Boehmermann, said it is unclear when a decision will be made about whether they will proceed with the prosecution.