The Pentagon said that insurgent violence was on the rise across Afghanistan and that international forces lacked the troops and resources to control the country''s south.

In a report to Congress, the US Defense Department described a dramatic increase in insurgent attacks in the spring and summer of 2008, saying the period marked the worst violence since the Taliban''s ouster in 2001.

A resurgent Taliban was challenging the Kabul government for control of the south and east of the country, "and increasingly in the west," the report said.

In the south, "where resources are not sufficiently concentrated, security cannot be established or maintained," it added.

"In such areas, the full military, governance and economic spectrum of the COIN (counterinsurgency) strategy cannot be implemented and the insurgents retain their hold on the local Afghan population."

The report, delayed for months pending the outcome of various strategy reviews, came as President Barack Obama weighed urgent military requests for up to 30,000 more US troops in Afghanistan, nearly doubling the US force there.

The report''s account of growing violence in the country was underscored by a suicide bombing on Monday that killed 25 policemen in the southern town of Tirin Kot.

"The Taliban regrouped after its fall from power and has coalesced into a resilient and evolving insurgency," the report said.

Insurgent attacks rose 33 percent last year and assaults along the country''s major highway increased by 37 percent compared to 2007, it added.