President Kibaki is on a crusade against corruption

The step is being portrayed as a key test of President Mwai Kibaki's crusade against corruption, which swept him to victory in December elections.

Justice Minister Kiraitu Murungi has said new evidence against Mr Chunga would form the basis of the tribunal, but did not give details.

"We have received confidential information touching on his conduct and performance as the Chief Justice of the Republic of Kenya," he told a Kenyan television station.

Allegations

According to President Kibaki's office, the investigation is linked to Mr Chunga's role as chief prosecutor in the 1980s.

It looks like Chunga has been pre-judged and found guilty Kanu MP William Ruto

Calls for his resignation have come from several groups, including human rights organisations and dissidents who were jailed.

There have also been allegations that Mr Chunga helped corrupt judicial officers.

In a speech on Tuesday marking the opening of parliament, Mr Kibaki said he wanted to fundamentally reform the judiciary to guarantee its integrity and independence.

An MP for the former ruling party, William Ruto, told AFP news agency that the tribunal was simply being used as an excuse to get rid of the chief justice.

"It looks like Chunga has been pre-judged and found guilty, and merely what they are doing is to rubber-stamp the decision," he said.