Iran on Monday urged "honesty" at crucial talks with world powers due to be held this week in order to defuse a tense international showdown over its disputed nuclear activities.

"We hope the P5+1 will come to the negotiating table with honesty, and we also will make an honest effort so that both sides reach a win-win conclusion," Foreign Minister Ali Akbar Salehi told the Iranian parliament's website.

World powers will hold a fresh round of nuclear talks with Iran in Istanbul on April 14, a spokesman for European Union foreign policy chief Catherine Ashton said Monday.

"We have agreed to launch talks in Istanbul on April 14," Michael Mann said.

The U.N. Security Council will have to take "very urgent and serious" action if Syria fails to meet an April 10 deadline to halt its military operations in protest cities, U.S. ambassador Susan Rice said Tuesday.

U.N. Security Council members negotiated a statement backing the April 10 deadline that U.N.-Arab League envoy Kofi Annan says Syria has accepted, as fierce clashes were reported between government forces and rebels.

British Ambassador Tom Fletcher on Monday hailed the Lebanese authorities’ efforts to maintain stability in the country by preventing any repercussions of the Syrian crisis on Lebanon.

Fletcher held a meeting with President Michel Suleiman on Wednesday at the Baabda Palace and discussed bilateral ties, the developments in the region, and the Arab League summit expected to be held in Baghdad on March 29.

British hostage Judith Tebbutt, kidnapped in Kenya over six months ago by gunmen who killed her husband, said Wednesday she was "happy" after she was released in Somalia to be flown to Nairobi.

Tebbutt, 57, was taken on September 11 from a remote Kenyan beach resort near the Somali border by assailants who shot dead her husband David in a late-night raid.

French Foreign Minister Alain Juppe has criticized EU foreign policy Chief Catherine Ashton's diplomatic efforts, calling for better policy coordination, in a letter obtained by Agence France Presse.

"We must improve the workings of the European external action service and the way they mix with diplomatic efforts of union members," he said in the letter sent to Ashton ahead of an EU foreign ministers' meeting Friday and Saturday in Copenhagen.

A Briton and an Italian taken hostage in northern Nigeria were apparently killed by their captors before the men could be rescued in a military operation Thursday, Britain's prime minister said.

"We are still awaiting confirmation of the details, but the early indications are clear that both men were murdered by their captors, before they could be rescued," David Cameron said in a statement.

Britain's defense secretary insisted on Thursday that the country's troops are committed to their mission in Afghanistan, after the number of U.K. personnel killed in the conflict passed 400.

Ministers have expressed fears that the deaths of six soldiers killed when an explosion hit their armored vehicle in the southwestern Helmand province on Tuesday evening would prompt new concern over the 11-year-long campaign.

World powers said Thursday that mooted upcoming talks with Iran focused on its nuclear program must be "serious", without pre-conditions and produce "concrete results."

"We call on Iran to enter, without pre-conditions, into a sustained process of serious dialogue, which will produce concrete results," said a statement on behalf of the United States, China, Russia, France, Britain and Germany, known as the P5+1.

Six British soldiers are missing and are believed to have been killed in Afghanistan after an explosion hit an armored vehicle, Britain's Ministry of Defense said on Wednesday.

"I have the tragic duty to report that six soldiers are missing, believed killed, during a security patrol," said British spokesman Lieutenant Colonel Gordon Mackenzie.