The U.S. Treasury on Thursday added 20 companies and individuals to its Iran sanctions blacklist, accusing them of supporting Tehran's nuclear efforts and helping the country avoid international sanctions.

The 20 include Iran-based transport and freight companies Aban Air, DFS Worldwide and Everex, as well as officials of the three, which the Treasury said work to get around bans on doing business with already-blacklisted Iran Air.

Shelling killed three people in the flashpoint Democratic Republic Congo city of Goma ahead of a visit by U.N. leader Ban Ki-moon on Thursday, the United Nations said.

Three shells were fired into the Goma district of Ndosho late Wednesday, killing three people and wounding 10, according to the U.N. humanitarian coordinator for DR Congo Moustapha Soumare. He did not say whether rebel or government forces were behind the shelling.

President Barack Obama Thursday laid out new guidelines for drone strikes abroad and launched a new bid to close the Guantanamo Bay prison, seeking to rein in a "boundless" U.S. war on terror.

In a major policy speech, Obama said the United States faced a new threat from "diverse" terror franchises and the growing threat of homegrown radicals, after putting al-Qaida in Pakistan and Afghanistan on the path to defeat.

A 7.4-magnitude earthquake struck 255 kilometers southwest of Tonga early Friday, according to the U.S. Geological Survey.

The under-sea quake struck at 5:19 am (1719 GMT Thursday) and sparked a tsunami alert, although no damage is expected due to its depth of 171 kilometers, according to the Pacific Tsunami Warning Center.

U.S. President Barack Obama on Thursday condemned the killing of a British soldier in London by two suspected Islamic extremists as "appalling" and "horrific."

"The United States stands resolute with the United Kingdom, our ally and friend, against violent extremism and terror," Obama said in a written statement.

The Organization of Islamic Cooperation condemned on Thursday what it called the "brutal and barbaric" killing of a British soldier in London in what authorities suspect was an act by Islamic militants.

A statement quoted the OIC's spokesman as reiterating the 57-member group's "strong and unwavering position against all forms of terror including hatred, violence and intolerance based on religion and faith."

Nigerian authorities have detained children in connection with the Islamist insurgency they are battling, but the government plans to release them under a peace gesture announced this week, a statement said Thursday.

The statement from an adviser to President Goodluck Jonathan comes after widespread allegations of Nigerian authorities carrying out indiscriminate arrests, unlawful detentions and extra-judicial executions in the fight against Islamist extremists.

A resurgence of fighting in Sudan's western Darfur region has driven 300,000 people from their homes so far this year, U.N. humanitarian aid chief Valerie Amos said on Thursday.

She was speaking at the end of a three-day visit to Sudan during which she visited a camp for displaced people in Darfur.

A special envoy from North Korean leader Kim Jong-Un told one of China's top officials Thursday that Pyongyang wants peace and is willing to pursue dialogue with key countries, state media reported.

Envoy Choe Ryong-Hae met Liu Yunshan, a member of the Chinese Communist Party's highest ranking body the Politburo Standing Committee, state television reported on its evening newscast.

The two men suspected of butchering a soldier on a London street in a gruesome Islamist attack were known to security agents, government sources suggested on Thursday.

Prime Minister David Cameron hinted that intelligence agencies would face probes into how the attackers slipped under the radar, but said police and security services "will not rest" until they bring those responsible to justice.