Iran's most senior judge has rejected calls for an international investigation into a spate of killings of Iranian liberals.

Ayatollah Mohammad Yazdi said in a sermon broadcast on Tehran radio that enemies of Iran were trying to make out that there was no security in the country.

He said killings on a far greater scale were going on in Algeria, and there were no calls for such an investigation there.

He said a number of people had been arrested and were being questioned about the murders.

The victims included at least three dissident writers and the opposition leader Dariush Foruhar and his wife Parvaneh.

Some supporters of President Mohammad Khatami have suggested the murders could be part of a campaign by hardliners to undermine his more liberal style of government, but conservatives say they have nothing to gain from destabilising the country.