Unidentified fighter jets bombed three Islamist militant bases in Somalia on Wednesday, residents and soldiers said, as neighbouring Kenya continued its assault on the rebels.

Kenyan troops entered Somalia six weeks ago vowing to wipe out the al Shabaab group, who it accuses of being behind a wave of kidnappings and attacks on tourists in Kenya.

Its air force has launched a series of strikes on what it says are rebel targets.

Jets bombed three al Shabaab bases around the town of Badade today, local elder, Hilowle Ali, told Reuters. We were all shocked and ran away. The town is now deserted.

A Somalia government soldier confirmed the raids and said there had also been strikes on Monday. He did not confirm that they were carried out by the Kenyan air force.

The jets bombed near the places where they bombed on Monday. It targeted al shabaab but we do not know the number of casualties, Yunis Macalim Amiin told Reuters.

Al Shabaab also said the raids had been carried out on Wednesday, and that seven bombs were dropped, but that it had suffered no casualties because its fighters had left the area.

Ethiopia, the Horn of Africa's major military power, also sent dozens of military trucks and armoured vehicles into central Somalia over the weekend, witnesses said.

It publicly denies its forces are inside its neighbour and has said a decision on whether to join the assault against al Shabaab in some form would be taken on Friday at a meeting of east African heads of state.

AMBUSHES AND POISONING

Though Kenya's advance on the militants started rapidly, it stalled quickly with its military blaming mud and heavy rains. Al Shabaab say daily hit-and-run raids and ambushes from its fighters are hampering the campaign.

The Kenyan police said on Wednesday that the rebels had ambushed one of its patrols in Liboi near the border with Somalia and close to the Dadaab refugee camp.

Our officers were attacked by bandits. I suspect and believe they are al Shabaab militants. Fortunately no officer lost his life, Leo Nyongesa, the police commander of Kenya's North Eastern Province, told Reuters.

Other officers in the area said two police officers were hurt in the attack and that another, who was critically injured, was airlifted to the capital Nairobi.

Al Shabaab guys were firing from both sides of the road, one officer said. But my colleagues managed to get out of the car, lay down on the ground and repel them.

A Somali military officer said the militants had also started to poison water pools that Kenyan and Somali soldiers used for drinking water.

Twenty of our soldiers are now very sick, 9 of them are serious, Abdikarim Ali Yusuf told Reuters.

An African Union peacekeeping force is largely responsible for keeping Somalia's weak transitional government from falling to al Shabaab. The Horn of Africa nation has not had a fully-functioning government since warlords toppled military dictator Mohamed Said Barre in 1991.

(Additional reporting by Sahra Abdi in Mombasa, Noor Ali in Garissa, Feisal Omar in Mogadishu and Barry Malone in Nairobi; Writing by Barry Malone; Editing by George Obulutsa and Janet Lawrence)