Kenya said on Sunday its troops had killed  dozens of Shebab Islamists in raids inside Somalia after the execution of 28 non-Muslim people on a Kenyan bus.

There was no independent confirmation of the strikes in response to Saturday's attack by the al-Qaida-linked group near Mandera, a northeastern town near the Kenya-Somali border.

A U.S.-Somali engineer who had come back to his birth nation to help rebuild the war-torn country has become the latest returning expat to be shot dead by suspected Islamic extremists, his relatives told Agence France Presse. 

The killing of Abdulahi Ali Anshur marks the latest in a string of murders of Somali diaspora who have returned to the country and were apparently targeted by Al-Qaeda affiliated Shebab militants because they work with the internationally-backed government.

Kenyan security forces on Wednesday carried out fresh raids on mosques in the port city of Mombasa searching for weapons and supporters of Somalia's Shebab militants, police said.

Grenades, ammunition and petrol bombs were seized in raids on the Swafaa and Minaa mosques, taking the total to four mosques searched since Monday in the tense city, officers said.

A Somali journalist working for a London-based television station became the third reporter to die in the war-torn country this year after he was killed Tuesday in the semi-autonomous Puntland region, police said.

Abdirisak Ali Abdi, who worked for Radio Daljir in Puntland and London-based Horn TV, was shot by a group of unidentified attackers in the town of Galkayo in the Mudug region.

Food rations vital for half a million refugees in Kenya will be slashed in half due to an aid shortfall, the United Nations said Friday in an appeal to donors.

"Cutting rations is the last resort," U.N. World Food Program (WFP) deputy chief for Kenya Paul Turnbull said, calling for $38 million more in cash, including an immediate $15.5 million to feed refugees until January.

Kenyan police said Wednesday they had arrested 10 suspected attackers, including two female suicide bombers, who had crossed into the country from war-torn Somalia.

"These 10 suspects were involved in recent terror attacks in Nairobi before they fled to Somalia, and now they have sneaked back," police spokeswoman Gatiria Mboroki told reporters.

The United States said Tuesday it was deeply concerned over a worsening power struggle between Somalia's president and prime minister, and pulled out of a international summit on the war-torn country.

Washington urged leaders to "rise above the political differences that divert from the important work of unifying the country", U.S. State Department spokeswoman Jen Psaki said in a statement.

While the Islamic State group is rapidly gaining support among jihadists worldwide, only marginal organizations and isolated individuals are formally expressing their allegiance, experts say.

Of the five main Al-Qaida offshoots -- in Afghanistan, Syria, Somalia, the Sahel and Yemen -- none has recognized the authority of IS chief Abu Bakr al-Baghdadi, who at the end of June proclaimed the establishment of a caliphate straddling Iraq and Syria, with himself as "leader for Muslims everywhere."

Twelve Somali men tried for piracy were acquitted Thursday in Mauritius for lack of evidence, court officials said.

"The prosecution did not provide enough evidence to prove the guilt of the accused," magistrate Wendy Rangan said, ending a year-long trial that began in October 2013.

Gunmen in the Kenyan port city of Mombasa have shot dead a moderate Muslim cleric, a vocal opponent of the radical preaching of Somalia's al-Qaida-linked Shebab insurgents, police said Wednesday.

The shooting in Kenya's second city is the latest in a series of killings of preachers, amid power struggles between rival Muslim factions.