At least four civilians, including two children, were killed in Mogadishu on Thursday when a volley of mortar shells landed close to Somalia's presidential palace, police and witnesses said.

The four dead were all members of the same family. The two youngsters and their grandmother were killed at once and their father died later of his wounds.

Somali government troops backed by African Union peacekeepers on Saturday recaptured the key port of Merka from Shebab insurgents, just one day after the Islamists swept into the city, the army and residents said.

"The Somali forces and AMISOM peacekeepers secured control of Merka again and now the situation has returned to normal," a Somali military official, Abdirisak Mohamed, told Agence France Presse by telephone from Mogadishu. 

One passenger is missing after a blast on a commercial airliner that ripped a hole in its fuselage shortly after take-off from Somalia's capital, the airline said Thursday.

"All passengers except one disembarked safely after aircraft landed at the airport," Daallo Airlines said in a statement. "Investigations are underway to ascertain the cause of one missing passenger."

A child was killed and six others wounded in Mogadishu on Monday after mortar shells targeted Villa Somalia, the main government complex which includes the presidential palace, police said.

Witnesses said they heard as many as five explosions.

Somalia said Thursday it had cut diplomatic ties with Iran amid a diplomatic crisis with Saudi Arabia.

A statement from Somalia's Ministry of Foreign Affairs announced the "decision to sever diplomatic ties" and gave Iranian diplomats 72 hours to leave the Horn of Africa nation.

One civilian was killed and another seriously wounded Thursday when mortars fired by Islamist Shebab insurgents exploded close to the presidential palace in Mogadishu, police said.

Explosions were heard in the heavily guarded government district around Villa Somalia, the presidential palace, around noon on Thursday.

Republican White House frontrunner Donald Trump's call for a 'shutdown' on Muslims entering the U.S. have been used by Somalia's Shebab in a jihadist recruitment video, a U.S. group that monitors extremist propaganda said Saturday.

The Al-Qaida-affiliated Shebab use an excerpt from Trump's December 7 speech calling for a "total and complete shutdown" on Muslims entering the U.S. to try woo Muslims in the West to wage jihad, the SITE Intelligence Group reported.

A suicide bomber blew himself up in a restaurant in Somalia's capital Mogadishu on Saturday, injuring three people, police and witnesses said.

The attack targeted the Village Restaurant, an eatery in the south of the city popular with journalists and government officials which was already hit by a deadly suicide bombing in 2012.

Several people were killed or wounded on Saturday when gunmen opened fire then detonated a car bomb on a busy road in Somalia's capital Mogadishu, police said.

"There was a drive-by shooting attack... then a car loaded with explosives was detonated after police reinforcements arrived," police official Ahmed Abdiweli told AFP.

Somali pirates have attacked two fishing boats, capturing one from Iran with 15 crew, an anti-piracy expert said Tuesday, adding that the vessel was now heading towards Somalia's coast.

"Two vessels were attacked," said John Steed from Oceans Beyond Piracy, which tracks ships that have been attacked and helps support hostages.