The UN Security Council on Wednesday boosted by nearly one half an African Union peacekeeping force in Somalia.
With this development , the council is seeking to press home a military offensive against Islamist rebels in the Horn of Africa country.
A resolution increasing the AMISOM force to 17,731 from 12,000 troops and police passed the council unanimously on the eve of an international conference in London to discuss measures to tackle instability in Somalia and piracy off its shores.
AMISOM had until now consisted of Ugandan and Burundian troops.
The new increase to a large extent is accounted for by bringing under its command Kenyan forces that entered Somalia independently last October to fight the al Shabaab rebels, blamed by Nairobi for attacks and kidnappings on Kenyan soil.
Diplomats said that other troops were expected to be brought in from Djibouti to bolster AMISOM, which although not a UN force, receives authorisation and much of its funding from the UN.
The force, which first entered Somalia in 2007, has claimed a series of recent successes against al Shabaab's fighters who had seized much of the east African country's centre and south.
Last August, AMISOM wrested control of the capital, Mogadishu.
In a further setback for the rebels, Ethiopian and Somali forces on Wednesday captured the key stronghold of Baidoa in central Somalia.
Ethiopian troops moved into Somalia in November but will not come under AMISOM and are expected to withdraw eventually, diplomats said.
Somalia collapsed into feuding between rival warlords, clans and factions after dictator Siad Barre was overthrown in 1991.
Its weak Western-backed interim government controls only limited areas.
Wednesday's resolution will increase the UN cost of supporting AMISOM from 250 million dollars to about 550 million dollars a year, excluding salaries for the soldiers, which are covered by the European Union, British Ambassador Mark Lyall Grant said.
He told reporters it would also give AMISOM a freer hand in its campaign.
“For the first time, it authorizes AMISOM to use all necessary means to reduce the threat from al Shabaab, and therefore to conduct more robust and offensive operations,'' said Lyall Grant, whose country sponsored the resolution.
The resolution also bans the export of charcoal from Somalia, a major source of funding for al Shabaab.
U.S. Ambassador Susan Rice and envoys from India and South Africa expressed disappointment that the resolution did not cover a naval element for AMISOM.
But Lyall Grant said fuel for four Kenyan vessels operating off Somalia's cost would be funded and their crews included in AMISOM, and only “ancillary costs in terms of wear and tear''would not be covered.