Washington, Dec 21 (IANS) US military commanders in Afghanistan are pushing for more ground raids across the border into Pakistan's tribal areas, leading to a debate over the "controversial" proposal.

The plan for forays into the militant stronghold in North Waziristan has not yet been approved, but military and political leaders say a "renewed sense of urgency" has taken hold, as the deadline - July 2011 - approaches for the Obama administration to begin withdrawing its forces from Afghanistan.

Military commanders have said that by using American Special Operations troops if militants were captured, brought back across the border into Afghanistan and interrogated, "it could bring an intelligence windfall", The New York Times reported Tuesday.

In interviews in Washington and Kabul, American officials said they were drawing up plans to begin ground operations to capture or kill leaders from the Taliban and the Haqqani network.

They said they are particularly "eager" to capture, as opposed to kill, militant leaders, who can offer intelligence to guide future operations.

The American operations, which earlier were "no more than a handful of forays" across the border into Pakistan, have "infuriated" Pakistani officials.

The US' "clandestine war" in Pakistan has for the most part been carried out by armed drones operated by the the Central Intelligence Agency (CIA).

In addition, Afghan militias backed by the CIA have carried out a number of secret missions into Pakistan's tribal areas.

These operations by Afghan operatives - called Counter-terrorism Pursuit Teams - were previously solely intelligence-gathering operations.

"The decision to expand US military activity in Pakistan - which would almost certainly have to be approved by President Obama himself - would amount to the opening of a new front in the nine-year-old war, which has grown increasingly unpopular among Americans," the report said.

"It would run the risk of angering a Pakistani government that has been an uneasy ally in the war in Afghanistan, particularly if it leads to civilian casualties or highly public confrontations."

Still, a senior American officer said: "We've never been as close as we are now to getting the go-ahead to go across."

The US officials declined to be identified by name, because they were discussing classified information.

One senior administration official said he was not in favour of cross-border operations unless they were directed against top leaders of Al Qaeda.

The Obama administration stepped up CIA drone strikes this year in the tribal areas. Since September, the spy agency has carried out more than 50 drone attacks in North Waziristan - compared to 60 strikes in the preceding eight months.