ISLAMABAD, Pakistan - U.S. President Barack Obama's plan to nearly double American troop numbers in Afghanistan needs to be matched by a similar surge in development workers and aid funding, NATO's top official said Thursday.

In a sign of the tough fight ahead in Afghanistan, NATO and Afghan troops earlier in the day killed up to 22 militants in airstrikes and ground battles near the border with Pakistan, officials said.

The U.S. has some 33,000 troops in Afghanistan battling a resurgent Taliban, but Obama is expected to send up to 30,000 more this year as his administration shifts its focus from the war in Iraq to Afghanistan.

Speaking in Pakistan, NATO's Secretary General Jaap de Hoop Scheffer said the new troops will take the fight to "places where it was not, or insufficiently, possible up till now."

Scheffer said other NATO allies should also boost troop levels in Afghanistan if possible, but also increase the number of civilian experts to help with reconstruction and development in a country brought to its knees by decades of war.

"I do see the need for the military surge President Obama is proposing, but it should be met with a civilian surge," he told reporters. "Let us not be under the illusion that extra U.S. force (alone) will do the trick."

NATO and U.S. officials have complained that Pakistan is not doing enough to fight extremists sheltering on its side of the Afghan border that they blame for attacks in Afghanistan.

Scheffer praised the coordination between NATO and Pakistan forces at the border, but said it could be improved. He also said Pakistani troops were committed to stamping out extremism in the frontier region.

There are nearly 70,000 foreign troops, including 55,000 under NATO command, in Afghanistan, the highest number since the Taliban were ousted from power in the 2001 U.S. invasion.

Officials say those numbers are low for counterinsurgency operations that involve fighting in vast spaces, with little or no government presence.

In the latest violence in Afghanistan, NATO and Afghan troops battled with militants in the eastern Khost province early Thursday, a spokesman for the alliance said.

NATO said 22 militants were killed during the operation, but Gen. Mohammad Zahir Azimi, the Afghan defense ministry spokesman, said eight militants died and two were wounded during the clash. It was not immediately possible to explain the difference in the count.

In the last three years Taliban fighters have taken control over wider areas of territory and continue to use roadside bombs in their campaign against Afghan and foreign troops. The number of such attacks rose 33 percent in 2008 compared to a year before, according to NATO.