KABUL, Afghanistan — Iranian weapons have begun flowing into Afghanistan, Defense Secretary Robert Gates said today, but he and Afghan President Hamid Karzai agreed involvement by Tehran cannot yet be proved.

Gates told a news conference at the presidential palace that he and Karzai had discussed the Iranian weapons issue.

"There have been indications over the past few months of weapons coming in from Iran," Gates said. "We do not have any information about whether the government of Iran is supporting this, is behind it, or whether it's smuggling, or exactly what's behind it."

The Iranian weapons are being supplied to the Taliban insurgents, he said, adding that some may also be headed to criminals involved in Afghanistan's drug trade. Gates did not specify what types of weapons were involved.

A NATO spokesman told reporters last week that a powerful type of roadside bomb like those used in Iraq, but never before seen here, was found recently in Kabul. The bomb, known as an EFP, or explosively formed projectile, was notable for its level of sophistication.

Asked separately whether he believed Tehran was behind the flow of weapons, Karzai suggested it was unlikely.

"There's no reason that any of our neighbors should support the Taliban," Karzai said. "We don't have any such evidence so far" regarding possible Iranian government involvement, he said, adding that relations between the two nations were improving.

"Iran and Afghanistan have never been as friendly as they are today," Karzai said.

Earlier in the day, during a stop at Camp Morehead, the head of the Afghan National Army said his country is pushing the United States to accelerate training and equipping his army so the Afghans can fight the Taliban on their own.

Gen. Bismullah Khan, the army chief of staff, told reporters traveling with Gates that the goal of attaining independence on the battlefield is essential.

"We don't have air support," he said through an interpreter, expressing frustration at the lack of an Afghan air force. "That is a very serious problem. We are looking forward to the day when we can fight the enemy independently."

He was asked how soon the army could reach that goal.

"We asked for it to be as soon as possible," he said. "I will ask the secretary of defense to expedite the process so we can do this. The only way to defeat the enemy is to become independent."