US says making big progress in eastern Afghanistan

* Commander says insurgent activity concentrated in south

* More troops headed for troublesome area

* Attacks up more than 70 percent this year (Adds NATO statistics on violence, paragraphs 6, 14-17)

By Andrew Gray

WASHINGTON, April 22 (Reuters) - U.S. and NATO forces are close to achieving "irreversible momentum" in their battle with insurgents in eastern Afghanistan, a senior commander said on Wednesday.

The Taliban and other insurgent groups have been strongest in eastern and southern Afghanistan but U.S. Army Major General Michael Tucker said security had improved this year in the east, where U.S. forces lead NATO troops.

He said about 80 percent of insurgent activity now took place in southern Afghanistan, where the United States plans to deploy thousands of troops in the coming months to reinforce British, Canadian, Dutch and other NATO soldiers.

"We're approaching what you could actually, cautiously term irreversible momentum in the east," Tucker told reporters at the Pentagon by videolink from Afghanistan.

Violence in Afghanistan is at its highest levels since U.S.-led forces toppled the Taliban in late 2001.

Insurgent attacks in the first three months of this year were up 73 percent on the same period a year ago, according to NATO statistics obtained by Reuters.

Tucker, deputy chief of staff for operations for NATO and U.S. forces, said the improvement was partly due to an influx of some 4,000 U.S. troops to the area earlier this year.

A pilot project creating a local community protection force has also begun in the east and economic development efforts are well established there, Tucker said.

"We have a combination of the right amount of forces... now to cover the area," he said.

Efforts by Pakistan to tackle militants on the other side of the border may also have helped reduce violence, he said.

STALEMATE IN SOUTH

In the south, Tucker reiterated the assessment of other senior U.S. officials that NATO and Afghan government forces were stuck in a stalemate with the insurgents.

"We just simply do not have enough forces to address the needs of the people down there," he said.

"The enemy, obviously, is taking advantage of that posture that we're certainly going to be addressing here very shortly."

The NATO figures paint a mixed picture of the security situation across Afghanistan.

Incidents involving improvised explosive devices -- the bombs used by insurgents -- rose 87 percent and deaths among international and Afghan forces were up more than 70 percent in the first quarter of 2009 compared to a year ago.

Attacks on Afghan officials and local government offices were also up, by 64 percent.

But civilian deaths were down 39 percent while kidnappings and assassinations declined by 30 percent.

The United States plans to deploy some 25,000 more troops to Afghanistan by the end of the summer, most of them to the south, in an effort to tackle the rising violence.

There are about 40,000 U.S. troops in Afghanistan now and around 32,000 troops from other nations, mainly NATO members. (Editing by David Storey)