Martin Schulz, the German president of the European Parliament, has cautioned Italians not to vote former prime minister Silvio Berlusconi back into power at the country's upcoming elections.

Schulz, who was once likened to a concentration camp guard by Berlusconi, cited investors' worries that a comeback by the media mogul might halt the reforms carried out by Prime Minister Mario Monti over the last 18 months.

"Silvio Berlusconi has already sent Italy into a tailspin with irresponsible behavior in government and personal escapades," Schulz told German daily Bild.

"Much is at stake in the forthcoming elections, including making sure that the confidence built up by Mario Monti is not lost," he added. "I am very confident that Italian voters will make the right choice for their country."

A Social Democrat, Schulz dared to criticise Berlusconi's policies in 2003. The then-prime minister responded by saying he would like to suggest Schulz for the role of Kapo in a film on Nazi concentration camps.

A Kapo was a camp inmate who used to supervise prison work gangs.

In another development, German Chancellor Angel Merkel's spokesman Steffen Seibert has dismissed Monti's remarks that she does not want the centre-left Democratic Party (PD) to win Italy's national election.

The outgoing Italian prime minster was responding to comments by Berlusconi, who has repeatedly attacked Merkel and claimed Monti had already agreed to join forces with the PD after the election "with Merkel's blessing".

In an interview with the Adnkronos news agency, Monti said that Merkel "fears the consolidation of parties from the left, especially in an election year for her, I don't think she has any wish to see the PD arrive in government".