The government has been urged to explain why Prince Andrew has met four foreign heads of state in the past six months and embarked on two full-scale government trade missions despite stepping down as the UK's special representative for trade.

The Duke of York announced last July that he would relinquish the role following criticism of his association with a convicted child sex offender, Jeffrey Epstein, and business connections with dictators including Colonel Gaddafi.

But palace records reveal he has remained at the heart of the UK government's export drive and has carried out 17 engagements in Saudi Arabia and China for UK Trade and Investment, an arm of the Department for Business, Innovation and Skills, since the announcement that he was no longer the special representative for trade.

On other trade trips endorsed by a cabinet committee, he had meetings with the emir of Qatar, the crown prince of Abu Dhabi, the prime minister of Malaysia and the presidents of Panama and Mongolia. In December, he met the king of Bahrain after the Bahrain Independent Commission of Inquiry published a report which, according to Human Rights Watch, "found a pattern of serious human rights violations that included the use of excessive force against peaceful protesters, arbitrary arrests and detentions, torture and ill-treatment of detainees".

Bahrain's state news agency said the meeting was to discuss "ways of promoting joint economic, trade and cultural cooperation".

The extent of Andrew's continued globetrotting emerged after he hosted a reception last week for UK trade delegates at the world economic forum in Davos, Switzerland. He also hosted a dinner for Indonesian businessmen and met Azerbaijan's dictator, President Ilham Aliyev.

"The government needs to come clean about this," said Labour MP Chris Bryant, the former Europe minister. "Last year, after a hail of criticism, they let it be known they were dispensing with the Duke of York's services, but now it seems to be business as usual. There should be no secrecy about whether the British taxpayer is paying for the duke's travel. If he is going to shake hands with the king of Bahrain, we need to know what is going on. People will continue to ask whose interests he is really representing."

When Andrew stood down from the role of special representative, he said he was planning to focus on developing business and technology skills in the UK, particularly among small businesses, promoting opportunities arising from the London Olympics and encouraging young entrepreneurs.

"I have decided that the label I gave myself when I began this role of special representative has served its purpose and is no longer necessary to the work that I do today and, more importantly, in the future," he said.

But he has retained high level access inside the coalition government and, in the past two months, has held private meetings with the foreign secretary, William Hague, the chancellor, George Osborne, and the international development secretary, Andrew Mitchell, as well as with Sir Jeremy Heywood, the new cabinet secretary, according to the court circular. He travelled with the trade minister Lord Green on an official trade mission to Saudi Arabia in September and they undertook several joint engagements, meeting Saudi leaders and businessmen.

One Whitehall official suggested Andrew's continued role reflected the British government's need for his influence in autocratic countries where leaders are not satisfied with contact with a changing roster of ministers.

"It is absolutely true that the duke has access at the highest levels which he uses to assist trade objectives and UK companies," said a spokesman for UKTI.

"He is particularly valuable in some parts of the world where continuity is valued over continually changing personnel."

In the past six months, he had meetings with 15 ministers from foreign governments in Qatar, Hong Kong and Saudi Arabia and took part in five dinners and lunches abroad in aid of British trade. Two weeks ago, he attended a reception for the Turkmenistan-UK Trade and Industry Council at the Foreign and Commonwealth Office.

His trade promotion activity has previously caused controversy. Shortly before the Arab spring, he invited Sakher el-Materi, a son-in-law of the now deposed Tunisian dictator, Zine al-Abidine Ben Ali, to lunch at Buckingham Palace. Materi, a businessman, has since fled Tunisia. Last year, Andrew lobbied an MP to help boost British business with Azerbaijan, an autocracy which has been accused of torturing protesters. He met Muammar Gaddafi in Tripoli on government trade business in November 2008 and lunched with his cabinet chief, Bashir Saleh, in London in July 2009 after giving a seminar at St James's Palace for Gaddafi's £5bn Libya Africa Investment Portfolio.

The UKTI and Buckingham Palace defended his continued trade role. "When the duke indicated he would give up the title of special representative, he made clear he saw promoting the UK in key markets as an important role," said a UKTI spokesman. "Nobody else has been appointed to this role and as a senior member of the royal family he would be entitled to hold meetings with Nick Baird [chief executive of UKTI] or Jeremy Heywood. All his overseas visits are considered by the royal visits committee to ensure maximum benefit to the UK."

A spokesman for the prince said: "As the prime minister said at the time of the announcement, HRH will continue to support and promote British business interests both at home and overseas. He will not have a specialist role as defined by government but will undertake trade engagements if requested. He has developed a particular interest in promoting skills and education for young people, and in apprenticeships and training. The duke continues to support business and investment in the UK and travels overseas in his capacity as a senior working member of the royal family, in exactly the same way as do others."

He said travel costs for the trips were covered by royal travel grant-in-aid, which is funded by the Department for Transport. A previous charter flight from Farnborough to Jeddah and back on a trade mission to Saudi Arabia was billed to the taxpayer at £28,767.