MOGADISHU - Fresh violence has claimed seven lives in Somalia, most of them in Mogadishu where the Ethiopian-backed government began security sweeps this week to find guns and insurgents, witnesses said on Wednesday.

In the provincial town of Baidoa, President Abdullahi Yusuf and Prime Minister Ali Mohamed Gedi were meeting supporters amid rumours among legislators that the president wants to push a no confidence vote in his prime minister through parliament there.

A growing rift between the pair has provided yet another headache for the Somali government, which has faced an Islamist-led insurgency all year in Mogadishu and is overwhelmed by humanitarian problems among its 9 million population.

Insurgents carried out one of their heaviest assaults late on Tuesday on a police station near Mogadishu's Bakara market, police spokesman Abdiwahid Mohamed Hussein said.

"Around seven in the evening, insurgents assailed Hawlwadag police station, firing rocket-propelled grenades and machine-guns," he told Reuters by telephone.

"The police fought them and killed two of the insurgents while seriously wounding one. He was rushed to Medina hospital, but he died before reaching the hospital."

Somalia has been without a functioning government since the fall of military dictator Mohamed Siad Barre in 1991. But violence has worsened since allied Somali-Ethiopian troops toppled an Islamist movement from Mogadishu in December last year.

Since then, Islamist-led insurgents have been carrying out near-daily attacks on government and Ethiopian positions.

On Wednesday morning, unknown gunmen shot three men in the south Mogadishu neighbourhood of Bulo Hubey.

"Early this morning two men armed with pistols shot three men in civilian dress around Bulo Hubey. Two of them were dead and the third one was in serious condition. The victims were government employees," said a witness who asked not be named.

Madina hospital sources confirmed one person who was gravely wounded in the head was admitted to the hospital.

"We received one person who has serious bullet wound on the head and his condition is grim," Dahir Dheere, a medical officer in the hospital, told Reuters.

Two civilians died and nine were wounded in the southern port city of Kismayu, after a landmine explosion targeted a security agent on Wednesday.

"Unknown gunmen remotely detonated a landmine when my car was passing at Alanley neighbourhood. My bodyguards, driver and I survived, but the gunmen opened fire at us after the blast and my bodyguards defended me," the security agent told Reuters on condition of anonymity.

Witnesses said the blast killed two. "They were cut to pieces," local inhabitant Fadumo Abdulahi Hirse said.