LONDON — Secretary of State Rice huddled with British officials yesterday to sketch out new goals for the troubled allied effort in Afghanistan at a time of deepening concern over the direction of the six-year-old conflict.

She met with Prime Minister Brown and Foreign Secretary David Miliband of Britain ahead of a series of top-level meetings of the Western alliance in the months ahead to settle on a long-term course for the mission.

Ms. Rice acknowledged that the allies need to strengthen their leadership, add combat troops, crack down on the Afghan opium trade, and extend the authority of the country’s weak central government further into the heartland. “It’s bumpy and there’s a lot of maturing that the alliance is having to do to do this,” she told reporters on her plane en route to London. Afghanistan “is a very difficult place to work.”

Ms. Rice insisted that the trend in the country is toward improvement, but acknowledged serious problems, including the Taliban’s ability “to wreak havoc on the Afghan people.”

In this, her assessment was more sober than that of President Bush, who in his State of the Union address last week described a country with a surging economy, advancing education system, and improving security. Mr. Bush did not mention in his address any of the problems confronting U.S. officials and their allies.

But during the last week, a series of reports by respected private groups — including one headed by a retired U.S. Marine general, James Jones, who also serves as an administration envoy — have concluded that the mission faces grave dangers because of the weakness of the Afghan government and the uneven commitment of NATO governments.

Majorities in all the contributing countries, except for America and Britain, want their troops to pull out of Afghanistan.

Last month, a plan to install a veteran British politician, Paddy Ashdown, as a “super envoy” to coordinate the mission was vetoed by President Karzai of Afghanistan as a threat to his nation’s sovereignty. Ms. Rice said she was confident the alliance would soon find another suitable candidate, most likely a European.

NATO allies, though determined not to relive the frictions they experienced in 2003 during the runup to the Iraq war, continue to struggle against pressure from U.S. officials and others for troop increases. Last week, the German government again firmly rejected suggestions to send its troops to confront violence in southern Afghanistan.

Canada, which has suffered a disproportionate loss of 78 soldiers from fighting in the Kandahar region of the south, has threatened to pull its troops unless other countries offer up more forces to help fight the resurgent Taliban and Al Qaeda.

There are now about 43,000 Western troops in Afghanistan, including about 26,000 Americans and about 7,800 British. The Pentagon last month announced plans to add about 3,200 Marines. Ms. Rice acknowledged that alliance planners are rethinking whether they will need to expand the size of the Afghan forces from what was originally envisioned.

She said needs include more people to train Afghan security forces, more effective action against drug cartels, and more roads to extend the influence of the traditionally weak central government. A super envoy is seen as one way to coordinate a welter of nonmilitary programs that are sometimes in conflict.

Later this week, NATO defense officials are to meet in Vilnius, Estonia, to discuss the Afghan mission. Mr. Bush will meet with alliance Secretary-General Jaap de Hoop Scheffer on February 29, the White House announced yesterday.