The Kenyan military said Sunday it killed 34 Islamic insurgents in two separate battles in neighbouring Somalia this weekend.

Military spokesman David Obonyo said two Kenyan soldiers were also killed and five others wounded when Shebab militants staged an ambush in Afmadhow, southern Somalia, on Saturday afternoon.

"21 Shebab militants were killed," Obonyo said, during what he described as a "fierce engagement".

Last week, the Kenyan army said it thwarted an attack on a military camp also at Afmadhow, killing 19 militants.

Obonyo said 13 more Shebab fighters were killed in a separate operation on Sunday in Sarira, north of the southern port town of Ras Kamboni, in which "a middle level Shebab commander" was also captured. In both incidents weapons, including AK-47 assault rifles and rocket-propelled grenades, were seized, Obonyo said.

In January, the Al Qaeda-aligned Shebab overran a Kenyan military camp in El-Adde, southern Somalia, manned by up to 200 soldiers, killing a large number of them although Nairobi has refused to say how many died.

The attack, which was widely regarded as Kenya's worst-ever military loss, was the third major assault on isolated bases manned by soldiers of the multinational African Union Mission in Somalia (AMISOM). Camps set up by Burundian and Ugandan troops have also been attacked with scores of soldiers killed each time.

As a result of the string of attacks AMISOM forces have withdrawn from a number of towns in southern Somalia and observers say the troops are largely in garrison mode, hardly venturing out into hostile territory.

Earlier this month, the US said it carried out an air strike on a Shebab training camp north of the Somali capital Mogadishu killing 150 fighters, a figure disputed by the insurgents.

The strike marked a shift in US strategy in Somalia which had previously focused on targeted killings of a small number of Shebab fighters with suspected direct links to Al-Qaeda, rather than mass attacks on foot soldiers.

The Shebab was ousted from Mogadishu in August 2011 and has since lost much of the territory it once held. Today, it concentrates on guerrilla attacks in the Somali countryside, bombings and suicide raids in towns and cities, and terror assaults in Kenya where small groups of Shebab gunmen have attacked a mall in Nairobi and a university in Garissa in recent years.

Shebab fighters have targeted AMISOM in Somalia because, in the absence of a functioning national army, the 22,000-strong force is the only protector of the internationally-backed government that the jihadists are committed to overthrowing.

Shebab attacks have increased in tempo since the start of the year, seen as an attempt to destabilise the government ahead of an election due later this year.