Vietnamese searchers on Sunday spotted possible aircraft debris after combing the sea for nearly 48 hours in search of a Malaysian passenger jet that vanished with 239 people aboard, officials said.

The discovery, which could confirm the worst fears of anguished relatives, came after Malaysia's government launched a terror probe into the Boeing 777's disappearance, investigating suspect passengers who boarded with stolen passports.

A Turkish court has freed five men accused of torturing and murdering three Christian missionaries in 2007, after the suspects' time in detention while on trial exceeded new legal limits, local media said Saturday.

The men walked free from their high-security prison in the eastern city of Malatya on Friday, according to Dogan news agency.

U.S. Secretary of State John Kerry on Sunday marked seven years since the disappearance in Iran of American Robert Levinson and urged Tehran to work with Washington to ensure his safe return.

"Robert Levinson disappeared seven years ago from Kish Island, Iran, during a business trip. He is one of the longest held American citizens in history," Kerry said in a statement.

African peacekeepers in Somalia operating with government forces have recaptured several strategic towns in the southwest from the al-Qaida-linked Shebab militia, officials said Sunday.

The African Union's AMISOM force announced it had launched a widescale offensive on Thursday against the Islamist fighters in areas near the Ethiopian border.

Pro-Russian activists attacked a pro-Kiev rally in Crimea with clubs and whips on Sunday as thousands took to the streets across Ukraine in rival demonstrations, escalating separatist tensions in the troubled ex-Soviet state.

Interim Prime Minister Arseniy Yatsenyuk vowed Ukraine would not cede "an inch" of its territory to Moscow after Russian forces and pro-Kremlin gunmen took over the Black Sea peninsula.

Tens of thousands of citizens turned out for an anti-nuclear rally in Tokyo on Sunday, as the nation prepares to mark the third anniversary of the Fukushima disaster.

Demonstrators congregated at Hibiya Park, close to central government buildings, before marching around the national parliament.

The Kiev authorities should block the presidential bid of the leader of Pravy Sektor, or Right Sector, movement, Dmytro Yarosh, the Russian foreign ministry's rights envoy said Sunday.

"The de facto authorities in Kiev and their Western protectors must close the road to power for the neo-fascist Yarosh and his supporters," foreign ministry rights envoy Konstantin Dolgov wrote on Twitter.

Afghan Vice President Marshal Mohammad Qasim Fahim, formerly one of the country's much feared warlords, died of natural causes on Sunday after a turbulent life that summed up the country's recent past.

Fahim, a leader of the Tajik ethnic minority, was senior vice president under President Hamid Karzai, who will step down at elections next month as NATO combat forces pull out of Afghanistan after 13 years of fighting the Taliban.

EU foreign policy chief Catherine Ashton said Sunday a final accord on Iran's nuclear program cannot be guaranteed, during a landmark visit that underscores a thaw in Tehran's ties with the West.

Ashton is in Tehran on an official visit that comes after Iran signed a preliminary deal in November with world powers under which it agreed to curb its disputed nuclear activities in exchange for sanctions relief.

Japan scrambled military jets Sunday to counter three Chinese military planes that flew near Japanese airspace, defense officials said.

One Y-8 information gathering plane and two H-6 bombers flew over the East China Sea, traveling in international airspace between southern Japanese islands and went to the Pacific Ocean before returning towards China on the same route Sunday morning, according to a spokesman at the Joint Staff of the Ministry of Defense.