The U.S.-led coalition accused the Taliban of using children as human shields during a battle in southern Afghanistan on Wednesday, while NATO said it was investigating a shipment of weapons intercepted near the border with Iran this month.

The fighting in Uruzgan province began when more than 20 insurgents armed with machine guns, rocket-propelled grenades and mortars attacked a joint Afghan and coalition patrol Wednesday morning, the coalition said in a statement.

As a coalition aircraft prepared to bomb the site, "coalition forces as well as the aircraft identified several insurgents in one compound using children as human shields," it said. Ground forces and the aircraft withheld fire to avoid injuring the children. It was impossible to independently verify the coalition allegations.

The troops fought Taliban trying to flee the compound, and more than a dozen suspected militants were killed, the coalition said. There were no reports of casualties to troops or civilians.

International forces have come under heavy criticism for causing civilian casualties during airstrikes on suspected militant locations. President Hamid Karzai has pleaded with foreign troops to coordinate more closely with their Afghan counterparts to prevent villagers from being hurt, and the number of civilian casualties has dropped recently.

Also Wednesday, a NATO spokesman said the coalition was investigating a weapons shipment recently intercepted by troops in Farah province near the Iranian border.

"Although we know that it came from the geographic area of Iran, there is no definitive indication that it came from the Iranian government. We're still evaluating what is contained in that shipment," spokesman Maj. Charles Anthony said.

A Washington Post report Sunday said the shipment seized Sept. 6 was being sent to the Taliban and included armor-piercing bombs similar to those that have been used in against foreign troops in Iraq. International troops intercepted two other shipments said to be from Iran earlier in the year.

NATO's top general in Afghanistan, Gen. Dan McNeill, has said there is no evidence linking the Iranian government to the shipments.

Last month, President Bush accused Iran of playing a destabilizing role in Afghanistan. But Karzai has said Iran's role is helpful.

During a visit to Kabul last month, Iranian President Mahmoud Ahmadinejad said he has "serious doubts" that his country is supplying weapons to Taliban insurgents. He called Afghanistan a "brotherly nation" whose stability is paramount for the region.

Karzai met with several former warlords-turned-politicians Wednesday and they agreed the government should hold peace talks with the Taliban, the president's office said.

NATO's top civilian envoy to Afghanistan, Daan Everts, said the alliance was "very interested" in seeing peace negotiations come to fruition and there appeared to be "growing interest" on the part of the Taliban and fighters from the militant group Hezb-i-Islami.

The possibility of peace talks gained momentum earlier this month when Karzai reiterated his long-held position that the government is willing to engage the Taliban diplomatically. But the Taliban leadership has set conditions the West is unlikely to accept — that U.S. and NATO forces first leave the country and that Shariah, a harshly conservative brand of Islamic law, must prevail in Afghanistan.

About 2,500 Afghan and NATO troops launched a new military operation Wednesday in Afghanistan's most violent southern province. The operation is in the Gereshk region of Helmand province, the site of the fiercest battles this year and the world's largest opium-producing region.

Insurgency-related violence has killed more than 4,500 people this year, including 3,100 militants and 600 civilians, according to an Associated Press tally of figures from Western and Afghan officials.

The U.S. Embassy in Kabul warned Americans that suicide bomb attacks were expected to increase during the holy month of Ramadan.

In the latest violence, a suicide bomber in Kabul blew himself up on the road leading to the U.S. air base in Bagram, the Interior Ministry said. No one else was hurt.

In southern Zabul province, Taliban militants killed three security guards protecting a construction project in Qalat, said Gulab Shah Alikhail, spokesman for the governor.