Castelli (left) has now unblocked Berlusconi inquiry

A no-confidence motion in Justice Minister Roberto Castelli was put before parliament on Tuesday over his decision to block an inquiry into Mr Berlusconi's business dealings.

The decision had prompted the centrist Christian Democrat (UDC) party to threaten to withdraw from Mr Berlusconi's four-party coalition.

But the storm has now forced the minister to change tack, says the BBC's David Willey in Rome, and the investigation into Mr Berlusconi's affairs will go ahead.

Series of rows

The row was the latest in a series of disputes within the coalition which threaten to destabilise the government during its crucial six-month presidency of the European Union.

The left-wing opposition brought the no-confidence motion in the Senate after Mr Castelli came under fierce criticism for his handling of the case.

UDC member Michele Vietti pitted himself against his boss

The row focuses on Mr Castelli's decision to block a Milan attorney's request for information from the United States about Mr Berlusconi's business activities.

The inquiries were being made into a case of alleged fraud involving Mr Berlusconi's Mediaset company.

Mr Castelli, of the far-right Northern League, blocked the request on the grounds that a new immunity law protected Mr Berlusconi from investigation.

But critics, including the Under Secretary for Justice and UDC member Michele Vietti, said the immunity law applied only to prosecutions and not investigations.

Mr Vietti had demanded the resignation of Mr Castelli.

'Growing discontent'

Our correspondent says there is growing political discontent about the immunity law - which was pushed through parliament just last month - and the increasing body of tailor-made legislation passed to protect Mr Berlusconi's private and business interests.

Mr Berlusconi is Italy's richest man, commanding a vast business and media empire.

He has been pursued in the courts for years over a variety of allegations.