Top US military commanders in Afghanistan are seeking to expand ground raids by Special Operations Forces across the lawless border in Pakistan's tribal areas, The New York Times reported Monday.

Amid growing US frustration with Pakistan's lackluster efforts at removing militants from strongholds there, the officials are proposing to escalate military activities in the nuclear-armed nation, the Times said in its online edition.

US forces have been largely restricted to limited covert operations and unmanned drone strikes in Pakistan due to fears of retaliation from a population that often holds strong anti-American sentiment in a country rife with militants.

Even these limited operations have provoked angry reactions from Pakistani officials. The drones are believed to be largely operated by the CIA.

Amid a looming July deadline for American troops to begin withdrawing from Afghanistan, military and political leaders pointed to a renewed sense of urgency.

Military commanders told the newspaper that the Special Operations plan -- which has not yet been approved -- could help them secure much-needed intelligence if militants were captured, brought back across the border into Afghanistan and interrogated.

US officials said they were particularly keen to capture -- rather than kill -- militant leaders from the Taliban or the Haqqani network in order to obtain intelligence about future operations.

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

But a senior official from President Barack Obama's administration said he did not favor cross-border operations, saying they have been mostly "counterproductive" unless they targeted top Al-Qaeda leaders.

The official also worried that political fallout in Pakistan over the operations could counter any tactical gains.

CIA-backed Afghan militias, previously believed to only carry out intelligence-gathering operations, have also crossed the border into Pakistan's tribal belt during secret missions, including one in which a militia destroyed a militant weapons cache, officials told the Times.

An Afghan political leader said one of the raids by the Paktika Defense Force -- one of six CIA-trained Afghan militias -- was initiated to capture a Taliban commander in Pakistan. The mission was ultimately unsuccessful but Pakistani militants opened fire on the Afghans.

Another CIA-backed force near the eastern Afghan province of Khost was recently deployed in the mountains along the Pakistan border, where it is due to try to intercept Taliban fighters during the winter, an American military officer told the Times, saying the militia has so far proven effective.

The full story is available at The New York Times.