BBC- Kenya says AU forces storm Somali rebel city of Kismayo
African Union (AU) forces have launched a beach assault and taken control of parts of Kismayo, the last major Islamist militant bastion in southern Somalia, Kenya's military says.
The port city has been a stronghold of the al-Qaeda-aligned group al-Shabab.
Al-Shabab spokesmen told news agencies that fierce fighting was now under way.
The Kenyan troops are part of the AU's Amisom force, which is trying to wrest control of the country for the newly elected UN-backed president.
Kenyan military spokesman Cyrus Oguna confirmed to the BBC that parts of Kismayo had been captured and the rest was expected to fall soon.
Mr Oguna said the joint operation of Kenyan Defence Forces and Somali government troops had begun at 02:00 local time (23:00 GMT Thursday) and was "basically amphibious".
Mr Oguna said: "We cannot give casualty figures at the moment, the damage has not been assessed, but I can tell you our forces are already in Kismayo."
He told the BBC: "There are some parts that still will be under the control of al-Shabab because we only got there a couple of hours ago, and Kismayo is a big city."
'Lightning and thunder'
Al-Shabab spokesmen said fierce clashes were taking place.
Al-Shabab commander in Kismayo, Sheik Mohamed Abu-Fatuma, told Agence France-Presse news agency: "The enemy using military boats have deployed hundreds of soldiers in the coast late last night and the mujahedeen fighters are engaging heavy fighting now with them. God willing they will be defeated."
Residents of Kismayo told Reuters news agency they could hear fighting outside the city.
One resident, Ismail Suglow, told the agency: "Now we hear shelling from the ships and the [militants] are responding with anti-aircraft guns.
"We saw seven ships early in the morning and now their firing looks like lightning and thunder. Al-Shabab have gone towards the beach. Many residents have taken their guns. The ships poured many AU troops on the beach," he said.
There are also reports that helicopters are attacking the town.
Earlier this week, Kenyan military jets had bombed the airport in Kismayo, destroying an armoury and warehouse used by Islamist militants.
Some 10,000 people had fled Kismayo in the past week, the United Nations refugee agency estimated, as Amisom, government troops and pro-government militia advanced on the city.
The BBC's Gabriel Gatehouse, in Nairobi, says that last week al-Shabab appeared to be making preparations for an exit, moving out fighters and equipment.
He says Kismayo is a significant source of revenue for whoever controls it and its loss would be a serious blow to the Islamists.
Kenya began its intervention in Somalia nearly a year ago after a spate of cross-border attacks blamed on al-Shabab.
Al-Shabab has been forced out of the capital, Mogadishu, and several other towns over the past year but still controls much of the countryside in south and central Somalia.
Since the overthrow of President Siad Barre in 1991, Somalia has seen clan-based warlords, Islamist militants and its neighbours all battling for control.