KANDAHAR, Afghanistan (Reuters) - Defense Secretary Robert Gates voiced concern on Monday about a flow of Iranian arms to Taliban insurgents in Afghanistan but said he had no information linking Tehran to the supply of weapons.
On his second visit to Afghanistan since taking over the Pentagon in December, Gates met Afghan President Hamid Karzai, who also said there was no evidence Iran supplied the Taliban.
"There have been indications over the past few months (that) weapons are coming in from Iran," Gates told a news conference with Karzai at the national palace in Kabul.
"We do not have any information about whether the government of Iran is supporting this, is behind it, or whether it is smuggling, or exactly what is behind it."
"But there clearly is evidence that some weapons are coming into Afghanistan destined for the Taliban, but perhaps also for criminal elements involved in the drug trafficking coming from Iran," he added.
U.S. officials accuse Iran of meddling in Afghanistan, and the Pentagon's top general said on Sunday that Iranian-made weapons had been found inside Afghanistan.
Gates' one-day visit to Afghanistan was aimed at assessing coordination within the U.S.-led coalition to ensure Afghanistan does not spiral into the kind of violence seen in Iraq.
He met Karzai and commanders in Afghanistan and viewed a commando training facility for Afghan soldiers. The former CIA director told Afghan officers during the visit that he remembered aiding anti-Soviet Afghan fighters in the area in the 1980s.
Gates then made his first visit to Kandahar in southern Afghanistan, host to some of the worst violence in Afghanistan, to meet U.S. troops and a regional commander behind closed doors.
Afghanistan is the world's largest producer of opium and supplies about 90 percent of the world's heroin. Authorities say heroin profits help fund the Taliban, waging an insurgency since they were ousted from government by a U.S.-led invasion in 2001.
Taliban violence has picked up in recent weeks following a traditional winter lull in fighting, despite the presence of nearly 50,000 NATO and U.S.-led coalition troops in Afghanistan.
Taliban suicide bombers strike several times a week and have recently moved into relatively peaceful areas in the north. The Taliban says it has trained hundreds of suicide bombers.
But Gates said the Taliban's expected spring offensive had not been as strong as some U.S. and NATO officials expected.
"I believe based on everything I've seen and everything I've heard, the spring offensive has been an Afghan-alliance offensive that has put the Taliban off their game," Gates said.
"The key is to sustain that."
"I am confident that the United States and our partners in the alliance will be here for as long as it takes," he said.
Karzai said Afghanistan's relationship with Iran had never been better, despite growing U.S.-Iranian tensions.
"We don't have any such evidence so far of the involvement of the Iranian government in supplying the Taliban," Karzai said.
In contrast, Afghan National Army chief Bismillah Khan said earlier in the day that Afghanistan was not getting enough cooperation from neighboring Pakistan.
"We have a relationship, of course, under the coordination of the United States," Khan said as he and Gates toured the commando training centre on the outskirts of Kabul. "The cooperation that we need, unfortunately, we don't get."
Khan said the two countries needed a better exchange of information and more joint training exercises.
Relations between the uneasy neighbors, both U.S. allies in its war on terrorism, have deteriorated in recent months. The worst violence in years erupted three weeks ago in a disputed border area in Afghanistan's southern Paktia province.
Afghanistan said Pakistan invaded its soil and killed 13 Afghans. Pakistan said Afghan troops started unprovoked firing on border posts.
(Additional reporting by Sayed Salahuddin)