By Yara Bayoumy and Njuwa Maina
NAIROBI (Reuters) - A grenade exploded in a Nairobi bar on Monday wounding 13 people, two days after Kenya's U.S. embassy warned of an imminent attack there as the east African nation fights Islamist militants in neighboring Somalia.
Kenyan Police Commissioner Mathew Iteere said there was no firm evidence yet to link the attack to Somalia's al Qaeda-linked al Shabaab rebels and senior officials from the group declined to comment.
Al Shabaab had threatened major reprisals if Kenyan troops did not leave the anarchic Horn of Africa nation and have launched large-scale attacks in the past in Somalia and Uganda, for which they have quickly claimed responsibility.
Nairobi blames al Shabaab for a wave of kidnappings of foreigners on Kenyan soil that have threatened the country's multi-million dollar tourism industry. The group has denied responsibility for the kidnappings, saying Nairobi is using them as a pretext for its military campaign.
Kenyan troops have advanced on several fronts in southern Somalia over the past week and are nearing the strategic transit town of Afmadow, where rebels have regrouped and reinforced their defenses.
Somali government officials and residents said Kenyan and Somali troops seized the town of Busaar about 40 km (25 miles) from border town El Wak on Monday. They said the rebels fled after a brief exchange of fire.
"We have peacefully seized Busaar town from al Shabaab and we are going to advance deeper into Gedo region. Kenyan troops are helping us," Colonel Mohamud Ali, a senior Somali government official, told Reuters by phone from Busaar.
France also denied on Monday reports that its navy had been involved in any bombardment on Saturday of the Somali town of Kuday, near the port city and al Shabaab stronghold of Kismayu. It said there were no French warships in the vicinity.
BLOOD AND BEER BOTTLES
The attack on the bar in Kenya's capital Nairobi came two days after the U.S. embassy warned of an imminent threat of reprisal attacks on places where foreigners are known to congregate, such as shopping malls and night clubs.
The bar, however, was small, run down and in an area where foreigners and well-off Kenyans rarely go drinking.
Witnesses said a man knocked on the door of Mwaura's bar early on Monday morning, hurled in the grenade and ran away.
"I heard an explosion, there was darkness and I thought the electricity had gone out but when I touched my face, there was blood," Lawrence Kioko told Reuters.
"The person who lobbed the grenade was not seen by anyone," Iteere told a media conference, adding that the device was Russian made and similar to one that killed two people in a bus station attack in Nairobi in December.
Reuters footage showed blood and beer bottles splattered on the ground of Mwaura's bar, which is frequented by laborers attracted by its cheap beer and spirits.
Blood stained a sink and overturned seats and debris littered the floor. Police cordoned off the area as an officer examined damage on the walls from the force of the explosion.
"There was a lot of blood, injuries, people were screaming, others confused, generally it was chaotic. It was a chaotic situation," bar owner Charles Mwaura told Reuters.
Simon Githai, communications manager at Kenyatta National Hospital, said 13 patients were brought in, nine had been discharged and two more were likely to be sent home soon.
"We are seeing ourselves admitting only two patients," he told Reuters.
Iteere said the police force had taken steps to boost security around potential targets within Kenya.
"We have heightened physical security on most of our vital installations, buildings, other social places like shopping malls, bridges, our fuel and petrol storage tanks," he said. "The police are not that many but our presence must be seen."
He also said police had found a number of AK-47 rifles in a weekend sweep of the Dadaab refugee camp in northern Kenya, home to more than 400,000 Somalis who have fled violence and famine at home.
SOMALI GOVT NOT PLEASED
Kenya is the latest of Somalia's neighbors to intervene militarily in a country that has not had an effective government for the last 20 years and where al Shabaab's presence has had serious security repercussions on the region.
Kenya has in the past initiated brief cross-border incursions but the latest operation is on a much larger scale, raising fears the country may be dragged into its neighbor's two-decade civil war.
While Somali government officials had said the two countries were cooperating in the fight against al Shabaab, President Sheikh Sharif Ahmed was more circumspect about the Kenya incursion on Monday.
"The Somali government and its people will not be pleased with Kenya's intervention," Sharif told reporters while visiting the front-line in Mogadishu. "We had not agreed with Kenya beyond helping us with logistics."
The Islamist militants have proven capable of launching large-scale suicide attacks within Somalia and outside and have warned they would bring the "flames of war" into Kenya.
This month, a suicide truck bombing claimed by the rebels killed more than 70 people when it exploded outside a compound housing government ministries in Somalia's capital Mogadishu.
The militants also claimed responsibility for a bomb attack in the Ugandan capital, Kampala, which killed 79 people watching the soccer World Cup final last year.
That strike, the militants' first on foreign soil, was in revenge for Uganda's contribution to the 9,000-strong AU peacekeeping force which is supporting Somalia's Western-backed government troops in removing the rebels from Mogadishu.
Nairobi is home to a large Somali community and last week security forces arrested and charged two doctors with being al Shabaab members. The militants said three of their clerics had been arrested in Kenya, one of whom is on a U.N. sanctions list, for recruiting new members and soliciting.
Al Qaeda struck east Africa in 1998, killing hundreds of people, mostly Africans, in suicide bombings of U.S. embassies in Kenya and Tanzania.
(Additional reporting by Noor Khamis and Fouad Khoeis in Nairobi, Abdirahman Hussein, Abdi Sheikh and Sahra Abdi in Mogadishu; Editing by David Clarke and Louise Ireland)