WASHINGTON — The U.S. commander in Afghanistan has told top Pentagon officials that Afghan security forces must expand faster and beyond current target levels to more quickly secure the country, defense officials said.

A dramatically stepped-up training program likely would require additional U.S. troops, but it is not clear how many, if any, extra trainers American commanders in Afghanistan will request.

Gen. Stanley McChrystal, the top U.S. commander in Afghanistan, is set to make a formal report with his recommendations in August. Defense officials emphasized that while McChrystal believes more Afghan security forces are needed, he has not yet made formal recommendations.

But the need for more Afghan security forces is clear — military leaders in Afghanistan have repeatedly said they need more Afghan army soldiers and police officers to help secure cities and villages.

"It isn't any secret that commanders want more Afghan troops," a defense official said. The official and others declined to be quoted by name because McChrystal's recommendations have not been made public.

The Afghan army, generally considered far more skilled than the police, has about 85,000 members and is already scheduled to grow to 134,000.

The Pentagon has accelerated the training schedule and military officials are debating how much faster they can go, as well as how many more American trainers the job would require.

"We don't want to put any numbers to it yet, but everyone knows expanding the Afghan national security forces is key to the counterinsurgency campaign," a military official said.

With about $800 million a year in overall revenues, the Afghan government cannot support the security forces it already has. Further expansion would require support for years to come from the United States or other nations.

Geoff Morrell, the Pentagon press secretary, would not discuss a conversation last week between McChrystal and Defense Secretary Robert Gates, and said it was "premature" to conclude what the recommendations would be.

"Everybody recognizes, and the secretary has said time and time again, the key to the U.S. ultimately leaving Afghanistan is to develop an Afghan military and police forces" capable of providing security, Morrell said.