(Adds meeting with Karzai, failed suicide attack, previous KANDAHAR)

By Sue Pleming

KABUL, Feb 7 (Reuters) - U.S. Secretary of State Condoleezza Rice and British Foreign Secretary David Miliband met the Afghan president and NATO commanders in Afghanistan on Thursday, in a joint visit to press reluctant allies to share the combat burden.

More than six years after U.S.-led and Afghan forces toppled the Taliban, the Islamist militia's resurgence and spiralling violence has led Washington to call on its allies to send more troops to Afghanistan, a country bigger in size and population than Iraq, but with only a third the number of foreign soldiers.

The Taliban fought back strongly last year. More than 6,000 people died in fighting in 2007, nearly 2,000 of them civilians.

Suicide and roadside bombings now occur on an almost daily basis targeting foreign and Afghan forces. Until 2005, suicide bombings were rare in Afghanistan.

"Frankly, I hope there will be more troop contributions and there needs to be more Afghan forces," Rice told reporters.

Rice, speaking against the backdrop of a NATO defence ministers' meeting in Lithuania, said alliance members needed to "come together to give enough military power to do what needs to be done on the front end of the counter-insurgency effort".

Rice and Miliband travelled to a sprawling base in the southern city of Kandahar, the birthplace of the Taliban and the main city in Afghanistan's most volatile region.

Rice and Miliband met NATO commanders on the frontline of the fight against the Taliban and afterwards addressed troops. Rice gave a rousing speech praising soldiers' bravery and sacrifice.

"This is a fight which will transform history," she said.

The pair then travelled to the Afghan capital to meet Afghan President Hamid Karzai and aid workers.

The United States and Britain are urging other NATO members to share more of the combat burden in southern Afghanistan where the Taliban insurgency is strongest.

Some NATO countries have bristled at public criticism from Washington over the refusal of a number of alliance members to position their forces in the more dangerous south.

Germany, for example, under its parliamentary mandate can send only 3,500 soldiers to the less dangerous north as part of the 42,000-strong NATO mission.

That means most of the fighting against the Taliban is shouldered by Canada, Britain, the United States and the Netherlands. They all want others to contribute more.

Canada has threatened to pull its troops out unless other allies come forward, and Poland's foreign minister has warned against "free-riding" in the alliance.

FIGHT BACK

"We want to spotlight the fact that we and several other allies are standing up and doing the tough job," said a senior U.S. official, who declined to be identified.

Few NATO officials expect major new contributions to be announced during the two-day meeting in Lithuania's capital Vilnius, but Washington wants to extract promises over coming weeks for reinforcements in the south by year-end.

Specifically, the United States wants assurances that allies will fill the gap when 3,200 U.S. Marines leave the south after a temporary deployment there later this year.

The Taliban have suffered heavy casualties whenever they have fought NATO forces, but have dramatically undermined the sense of security with a wave of suicide bombings across the country.

A Taliban suicide bomber wounded an Afghan civilian in eastern Afghanistan on Thursday in a failed attack on a foreign troop convoy and two other suicide bombers died in the western province of Farah when their explosive vests blew up as they were preparing for an attack, officials said.

NATO commanders believe the tactic is aimed at sapping the will of European governments to keep troops in the country in the face of popular disquiet over the mission.

More than 200 NATO troops died last year in Afghanistan.

Some analysts see the NATO force as far too small.

"There are no clear indicators that the NATO countries, including the United States, are willing to invest a level of combat forces that would lead to success in southern Afghanistan," said Sean Kay, chair of International Studies at Ohio Wesleyan University. (Editing by David Fogarty)

AlertNet news is provided by