Canadian military officials in Afghanistan say they're concerned about the influx of improvised explosive devices (IEDs) entering the country from Iran. But they contend there is no evidence the Iranian government is behind the export of weapons that end up in the hands of Taliban fighters.

During a visit to Afghanistan over Christmas, Defence Minister Peter MacKay surprised reporters by accusing Iran of supplying IEDs to Afghan insurgents.

But the general in charge of Canadian forces in the country says the source of parts used in the IEDs is unclear.

"There were parts coming from Iran, there was parts also coming from other countries" said Brig.-Gen. Guy Laroche.  "I cannot say from what I see on the ground that Iran is behind that."

NATO officials also say they are seeing weapons from Iran but remain cautious about naming a source for the IEDs in Afghanistan.

"The border between Iran and Afghanistan is relatively porous and we have noticed that weaponry and ammunition does come across that border," said NATO spokesperson Antony McCord.

MacKay -- who was accompanied on his trip by David Wilkins, the U.S. Ambassador to Canada -- said Canada had spoken to Iran about the issue on several occasions. But it was the first time that Canada had voiced its concerns publicly.

MacKay said that Canada was "very concerned that weapons are coming from Iran. We're very concerned these weapons are going to the insurgents and keeping this issue alive."

The Iranians say Canada is merely repeating a familiar U.S. message. Washington has accused Iran of supplying weapons and parts for IEDs to insurgents in Iraq and Afghanistan. The U.S. has also claimed that Iran has a nuclear weapons program -- an allegation that was refuted last month by a U.S. intelligence report.

The Iranian government has denied allegations that it is behind the weapons being smuggled into Afghanistan. Iran's Shiite government has historically had frosty relations with the Taliban, which is the main insurgent force fighting against NATO and Afghan national forces. The Taliban and al Qaeda insurgents are composed of Sunni Muslims, who have traditionally been antagonistic towards Iran's Shiite Muslims.

Iran's consul in Kandahar told Â鶹´«Ã½ that the presence of thousands of foreign troops in Afghanistan is destabilizing the country, and that was a threat to Iran's national security. The Iranian official added that Iran will defend itself against any dangers.

Afghan officials have said they have good relations with Iran and they are not sure who is behind weapon-smuggling operations along their shared 1,000-kilometre border.

Omar Samad, the top Afghan diplomat in Canada, told Â鶹´«Ã½net following MacKay's comments that his country is working with its partners, including Canada, to find an answer.

IEDs were responsible for 75 per cent of Canadian deaths in Afghanistan last year.

With a report from CTV's Murray Oliver