LONDON: British Prime Minister David Cameron ordered an inquiry on Monday into whether the head of his Conservative party broke rules by taking a business partner on an official visit to Pakistan.

Sayeeda Warsi, the co-chairman of the centre-right party and a cabinet minister without portfolio, apologised for failing to disclose that Abid Hussain and she were both shareholders in a food company before the 2010 visit.

“I accept that I should have made officials aware of the business relationship between Hussain and myself, and for this I am sorry,” she wrote in a letter to Cameron.

“I regret that this failure may have caused embarrassment to the government.” But Cameron called in Alex Allan, his independent adviser on ministerial interests, to “consider the issues that have been raised with respect to the ministerial code and to provide advice to me as rapidly as possible”.

Under the code, ministers must avoid any conflict of interest, or the appearance of such a conflict.

Warsi, who is the first female Muslim minister in Britain and sits in the upper House of Lords in parliament, has been under mounting pressure over separate allegations about her expenses claims for house rental.

Several parliamentarians were jailed after The Daily Telegraph newspaper published details of claims in 2009 revealing how taxpayers' money was used for lawmakers' widescreen TVs, furnishings and even an ornamental duck house.

Cameron's decision to order an investigation into Warsi also raises awkward questions about why he did not take the same action against culture minister Jeremy Hunt over his controversial dealings with Rupert Murdoch's media empire.

Hunt has faced calls to resign over his communications with Murdoch's US-based News Corp. at a time when he was supposed to be making an impartial decision on the company's bid for full control of British pay-TV giant BSkyB.