Michael Hartmann, the MP for Wackernheim, in west Germany, has refused to resign his seat

A leading German politician who confessed to using crystal meth yesterday attempted to explain his actions, by claiming that they improved his performance as an MP.

Michael Hartmann, 51, admitted buying small amounts of the powerful stimulant and using it for a month.

The Social Democratic Party MP for Wackernheim, in western Germany, has refused to resign his seat after a police raid on his home failed to find any trace of the drug and he is not, so far, facing any charges.

Mr Hartmann issued a statement through his lawyer following days of silence after he was named last week by a dealer under surveillance by German police.

He said that he thought that using small quantities of crystal meth would help him to