Prime Minister Gordon Brown said he would host an international meeting later this month to support the troubled nation, where militants are believed to have trained the Nigerian man accused of trying to blow up an airliner over Detroit on Christmas Day.
US President Barack Obama yesterday confirmed that the 25 December plot was hatched by al-Qaeda as his administration pledged to double financial aid to Yemen.
Speaking while on holiday in Hawaii, Obama said: "The investigation into the Christmas Day incident continues, and we're learning more about the suspect.
"It appears that he joined an affiliate of al-Qaeda, and that this group – al-Qaeda in the Arabian Peninsula – trained him, equipped him with those explosives and directed him to attack that plane headed for America."
Al-Qaeda in the Arabian Peninsula, effectively the Yemen branch of Osama bin Laden's network, has already claimed responsibility for the attempt by Nigerian student Umar Farouk Abdulmutallab to ignite explosives hidden in his underwear as Flight 253 from Amsterdam approached Detroit.
The UK and US governments are today expected to announce plans to boost their joint funding for counter-terrorism police and improved coastguard patrols in Yemen, which neighbours Saudi Arabia and is just a short ferry ride from troubled Somalia.
Brown said: "The international community must not deny Yemen the support it needs to tackle extremism."
The increase in US backing for Yemen was announced in Baghdad by General David Petraeus, head of the US Central Command.
"We have, it's well known, (provided] about $70 million in security assistance last year. That will more than double this coming year," Petraeus said.
US officials have said they are looking at ways to expand military and intelligence co-operation with Yemen in order to step up a crackdown on al-Qaeda militants there.
But a Pentagon spokesman last week described as "grossly exaggerated" a report that Washington was preparing retaliatory strikes after the Detroit plane incident.
Both the UK and US are also today expected to announce that they will work together in the United Nations Security Council to call for beefed-up peacekeeping troops in wartorn Somalia.
The African nation's hardline Islamist rebel group al-Shabaab last week said it was ready to send reinforcements to al-Qaeda in Yemen should the US carry out military strikes.
Compounding the challenge from al-Qaeda, Yemen faces a separatist rebellion in the south and an insurgency by rebels from the minority Shiite Zaidi sect in the north.
A Yemeni government source said 11 Shiite rebels, who he described as "terrorists," had been killed in clashes with the military and security forces.
The conflict, which has killed hundreds and displaced tens of thousands, drew in neighbouring Saudi Arabia in November when rebels staged a cross-border incursion into the world's biggest oil exporter. The multiple security threats facing Yemen's government have intensified Saudi and Western concern that it could turn into an al-Qaeda haven and launch pad for international attacks – a role played by the Taleban regime in Afghanistan in the run-up to the 11 September attacks on the US in 2001.
Yemen's foreign minister Abubakr al-Qirbi last week admitted there could be up to 300 al-Qaeda militants in his country, some of whom may be planning attacks on Western targets.
Yemen last night welcomed Brown's plans for a 28 January meeting to discuss countering extremism in the country, the south of which was ruled by Britain until 1967.
A spokesman for the Yemeni government said: "This is a step in the right direction to intensify international efforts to support Yemen's development. Eradicating poverty, extremism and unemployment in developing societies is the way to end radicalism."