Afghan forces will be "good enough" to take over their country's security by the end of 2014, even though only a small number of them now operate independently from NATO-led troops, a top US general said Wednesday.

Lieutenant General Curtis Scaparrotti, deputy commander of US forces and the head of the NATO-led force's joint command, acknowledged that Afghan army and police still had a way to go before overseeing security without major assistance from foreign troops.

But he rejected a more pessimistic view voiced by some in and outside the US military, including US Army Lieutenant Colonel Daniel Davis, who accused his superiors of glossing over the failings of Afghan forces in an article published this week.

Some US soldiers in the field have been critical of their Afghan partners, Scaparrotti told a news conference, but the Afghan forces have been built up over a short period and could not be compared to a US standard.

"At times, a (US) private will tell me they're not that good. But a private's looking at it from the perspective of how he's trained, or the Marine's trained, and the standards are very different," the general said.

"I can tell you personally from experience and from feedback from others, these soldiers will fight, particularly at the company level. There's no question about that," he said.

"And they're going to be good enough, as we build them, to secure their country and to counter the insurgency that they're dealing with now," he said.

The state of Afghanistan's security forces has taken on growing importance as the United States and its allies pursue a troop drawdown and after Washington announced last week it would shift from a combat to a training role as early as mid-2013.

President Barack Obama was briefed on efforts to build "capable" Afghan security forces at a meeting on Wednesday that focused on Afghanistan, including efforts to broker a possible peace settlement with the insurgency, the White House said in a statement.

The discussions also covered preparations for a NATO summit in Chicago later this year, when the alliance plans to present more details of its plan to hand over security for the whole country by the end of 2014.

At the Pentagon, Scaparrotti said 29 Afghan army battalions and seven police units -- only about one percent of Afghan forces -- could now conduct operations independently, with support from coalition advisors.

"So it's a very low number," he said.

But about 42 percent of Afghan forces were ranked as "effective" with help from coalition advisers, said the general, calling it an encouraging sign.

The transition effort that will put Afghans in the lead was still in its "early stages," said the general, adding the security forces remained reliant on NATO-led troops for logistical support and maintenance of equipment.

He said the Afghan army and police had growing pains after a dramatic expansion, with the force doubling in about 18 months.

NATO allies hope to have the Afghan security forces grow to 352,000 by October, including 195,000 in the army and 157,000 in the police.

The Afghan forces came in for harsh criticism from Davis, the whistleblower officer who has openly questioned the Pentagon's portrayal of the war effort and the efficacy of the local army and police.

Writing in the Armed Forces Journal, which is not an official publication of the military, Davis described incidents during his 12-month tour that portrayed Afghan troops as reluctant to fight or even colluding with the Taliban.

Scaparrotti said the article represented only one person's view and that war commanders draw on a broad range of information. But he said military leaders are taking a realistic view of the war and not trying to avoid uncomfortable facts.

"We have to ...try to be very accurate about what we see, and what we understand the battlefield to be, and not treat it as we want it to be," he said.