LONDON, Feb. 10 (Xinhua) -- The Haitian ambassador to the United Kingdom, Bocchit Edmond, on Saturday said that the Oxfam, an international anti-poverty charity, should publicly apologize for some members of its staff using prostitutes while working in Haiti after the 2010 earthquake.

Edmond, speaking to BBC, criticized the charity for failing to inform the Haitian authorities about what happened and said it should publicly apologize.

"It is really shocking, it is shameful, and it is unacceptable," he said. "I think Oxfam should look into itself deeply if they want to rebuild that trust they had."

The ambassador made the remarks a day after British Prime Minister Theresa May called for a "full and urgent investigation" into the charity, which receives tens of millions of pounds in aid.

The Haitian government is expected to summon Oxfam representative in Haiti, he said, adding that a rented villa in the island country was used for the sex trade.

The ambassador said that he believed that the charity did cover up, but the charity denied the misconduct allegations. Oxfam said that it investigated the allegations in 2011, and fired four people and allowed three others to resign after the probe.

British media reports said Friday that the charity offered its former Haiti country director, Roland van Hauwermeiren, a "phased and dignified exit" after he admitted using prostitutes at a villa rented for him by Oxfam with charitable funds because sacking him would have "potentially serious implications" for the charity's work and reputation.

Media reports also said that the misconduct allegations against seven former Oxfam staff included the downloading of pornography. Oxfam's investigation into the sex abuse claims was hampered by a "determination to keep it out of the public eye".

"The reports of what is unacceptable behavior by senior aid workers in Haiti are truly shocking," a spokeswoman for British Prime Minister Theresa May said. "We want to see Oxfam provide all the evidence they hold of the events to the Charity Commission for a full and urgent investigation of these very serious allegations."

Meanwhile, the British Department for International Development lashed out the charity for its lack of transparency as questions swirled about the cover-up.

"If wrongdoing, abuse, fraud or criminal activity occur, we need to know about it immediately, in full," the British agency said. "The way this appalling abuse of vulnerable people was dealt with raises serious questions that Oxfam must answer."

At the time of the scandal, Oxfam had 230 staff in Haiti, which was recovering from the earthquake that left some 220,000 people dead, 300,000 injured and 1.5 million homeless.

Back in 2011, Oxfam, like many other international aid bodies, was engaged in providing emergency support to Haiti which the previous year was hit by the devastating earthquake.

The disclosure that some men in the scandal obtained jobs in other emergency zones raised alarm about the quality of recruitment processes and background checks in the aid world.

Oxfam suggested that some of those it had disciplined had conspired to produce bogus employment references. A spokesman said, "Oxfam has not and would not provide a positive reference for any of those that were dismissed or resigned as a result of the case."

At present, Oxfam, which receives 300 million pounds (about 414 million U.S. dollars) a year from governments and in public donations, insisted there had been no cover-up, but it was facing growing political pressure to make full disclosure of its evidence from Haiti to the Charity Commission.

Oxfam chief executive Mark Goldring apologised on Saturday, saying he was "deeply ashamed of Oxfam's behavior".

"Everybody -- the 25,000 staff and volunteers -- are compromised by this, the hundreds of thousands of people who support Oxfam every month are compromised by this, and to everybody I apologize," he told BBC.

"What I'm apologizing for is that nine Oxfam staff behaved in a way that was totally unacceptable and contrary to our values, and that led much more responsible staff to make decisions which are now seen by some as being marginal or inappropriate," he said. "But I'm not apologizing for the fact that Oxfam continued its work in Haiti."

Haiti is one of the poorest countries in the Western hemisphere, more than half its inhabitants survive on less than 1 U.S. dollar per day.