KABUL—At least 10 civilians, including eight Turkish nationals, are feared to be in the custody of the Taliban after a civilian cargo helicopter made an emergency landing in a remote area of eastern Afghanistan on Sunday, Afghan and Turkish officials said.

Eight Turkish nationals have been detained in Afghanistan after their chartered Mi-8 helicopter was forced to land, said Levent Gumrukcu, a spokesman at the Turkish Foreign Ministry in Ankara. He added that two crew members had also been captured.

Taliban spokesman Zabihullah Mujahid disputed the Turkish statement and claimed on Monday that the insurgents captured alive 11 "foreigners" aboard a "U.S.-NATO helicopter," which he said carried "American military officers" and two translators before being forced to land by bad weather.

"The foreign forces, by disassociating themselves from the helicopter, are trying to make it seem as the detainees are civilians but denial will not benefit them as all were captured while wearing American military uniforms," Mr. Mujahid said.

A Western official said that there were no Americans aboard the chopper. In addition to the eight Turks, it carried a Russian and a Kyrgyz crew member, and one Afghan citizen, he said.

Turkish authorities assumed that the crew and passengers were in good condition because they hadn't received any information to the contrary, Mr. Gumrukcu said. "We're working closely with Afghan officials on the issue," he said.

Afghan officials said on Monday that a chartered helicopter had been forced down by bad weather in the Mangal valley, an isolated area of Logar province south of Kabul. A senior provincial security official said the aircraft had been secured by government forces, but that all personnel on board had been abducted by the Taliban.

The valley, the official said, "is a very remote area and hard to access."

While predominantly Muslim Turkey is a member of the U.S.-led coalition in Afghanistan, its troops don't usually take part in combat operations. Ankara has also been generally supportive of Islamist political parties in countries such as Egypt, Tunisia and Morocco.

Recognizing Turkey's growing regional stature, the Taliban last month released a Turkish engineer who had been detained two years earlier for being involved in "suspicious activities." The Taliban last month said the man was released to Turkish representatives in the Sah Padar area of Tagab district, Kapisa province, as a "goodwill gesture."

German Brig. Gen. Günter Katz, spokesman for the U.S.-led International Security Assistance Force, said the coalition was assisting the Afghan authorities in efforts to recover the missing helicopter.

Both the U.S.-led coalition and the international community in Afghanistan rely heavily on contracted aircraft to move supplies, personnel and equipment around the country. Cargo helicopters and fixed-wing planes provide supplies to military bases and support reconstruction projects, particularly in areas where it is too dangerous to move by road.

The Russian-designed Mi-8 helicopter was chartered by Khorasan Cargo Airlines, Mr. Gumrukcu said. According to a company website, Afghanistan-based Khorasan operates Mi-8 T and Mi-17 helicopters and An-26 twin-engine turboprops.

A representative of Khorasan in the United Arab Emirates declined to comment. The company's Afghanistan office couldn't be reached by telephone.

The U.S.-led military coalition referred inquiries on the matter to the Turkish embassy in Kabul; the embassy wasn't immediately able to comment.

—Habib Khan Totakhil contributed to this article.

Write to Nathan Hodge at nathan.hodge@wsj.com and Emre Peker at emre.peker@dowjones.com