All four gunmen from Somalia's Al-Qaida linked Shebab who carried out the Kenyan university massacre earlier this month were Kenyans themselves, reports said Thursday.

The militants attacked the university in the northeastern town of Garissa on April 2, lining up non-Muslim students for execution and killing 148 people in what President Uhuru Kenyatta described as a "barbaric medieval slaughter".

Two Vietnamese fighter jets crashed into each other during a training exercise over the contested South China Sea on Thursday, state media have reported, without confirming the fate of the two pilots.

The Sukhoi Su-22 fighters crashed offshore from southern Binh Thuan province's coast during a diving practice, Thanh Nien newspaper said.

The Turkish government on Thursday said a Turkish-Armenian advisor to Prime Minister Ahmet Davutogou had "retired", days after he caused a furore within the ruling party for describing the mass killings of Armenians during the Ottoman Empire as genocide.

The government denied any link between the departure of Etyen Mahcupyan and the looming 100th anniversary on April 24 of the start of the 1915 killings of Armenians, which Yerevan regards as genocide.

Kenyan youths have begun construction of a security barrier along the vast and porous border neighboring war-torn Somalia, although critics have dismissed the project as infeasible, reports said Thursday.

The proposed barrier is the latest in a string of measures Kenya has announced to stem attacks by Somalia's Al-Qaida-linked Shebab insurgents in the wake of a university massacre in the northeastern town of Garissa.

Armenian forces on Thursday killed an Azerbaijani soldier in the latest breach of a ceasefire between the arch-foes locked in a simmering conflict over the disputed Nagorny Karabakh region, officials in Baku said.

"Armenian forces have yet again violated the ceasefire and killed an Azerbaijan army warrant officer," Azerbaijan's defence ministry said in a statement without giving further details.

The search area for flight MH370 will double in size to encompass a vast Indian Ocean corridor if wreckage remains elusive, Malaysia, Australia and China said Thursday, asserting their commitment to finding the plane.

Meeting in Kuala Lumpur, ministers from the three countries said the deep-sea zone now being scanned for signs of the ill-fated Malaysia Airlines jet would be expanded to 120,000 square kilometers (46,300 square miles) if the current area comes up empty.

Sixteen Myanmar soldiers died in a major offensive to flush rebels from a strategic hill-top in the northeastern region bordering China, state media said Thursday, as fighting with ethnic insurgents nears its tenth week. 

Scores of soldiers and ethnic Kokang rebels have died since conflict erupted in the remote region of Shan state on February 9, while tens of thousands of people have fled across the frontier into China.

An Indonesian fighter jet caught fire just before take-off on Thursday, prompting the pilot to jump to safety as flames and thick smoke engulfed the plane, officials said. 

The pilot escaped with minor injuries and is now being treated in hospital after leaping from the blazing F-16 aircraft, which was about to take off from an airbase in the capital Jakarta.

Authorities issued an alert for several Mexican states Wednesday after thieves snatched potentially deadly radioactive material used for industrial radiography.

The iridium-192 source, marked X-571, was inside a container when it was stolen on Monday from a truck in Cardenas, a town in southern Tabasco state, the interior ministry said in a statement.

An anti-corruption protester was arrested after he landed his mini helicopter on the U.S. Capitol lawn Wednesday and piloted it through Washington's no-fly zone, triggering a national security investigation and shocking bystanders.

The Federal Aviation Administration said it is investigating the incident along with other U.S. authorities, adding that the pilot was not in touch with air traffic controllers while in the air.