Kabul, July 13 (RHC)-- At least 25 civilians have been killed and sixteen more wounded in a car bomb explosion in Afghanistan's eastern city of Khost, authorities say.

Initial reports said that only 18 people were killed and 6 others injured, but the toll was later raised by officials. The bomb exploded at a military roadblock near the entrance to Forward Operating Base Chapman, also known as Camp Chapman, while people were rushing to get home for iftar, said Faizullah Ghairat, the Khost city police chief.

No group or individual has yet claimed responsibility for the blast but Afghan officials often blame the Taliban militant group for such incidents.

A statement from the NATO mission in Afghanistan said it was "aware" of the blast, but did not elaborate on the incident. This is not the first time that Camp Chapman was hit by a bomb attack. In 2009, the military site was the target of an explosion claimed by al-Qaeda.

In that attack, seven CIA American officials were killed in the deadliest assault on the U.S. agency since 1983, when eight officers died in an attack on a military base in Beirut.

The Taliban has stepped up its campaign of violence in recent months, taking advantage of the warmer weather of spring and summer.

However, it is ordinary Afghans who are paying the price, the United Nations Assistance Mission in Afghanistan (UNAMA) said in a report released earlier this year. Almost 1,000 civilians were killed during the first four months of this year, a sharp jump from the same period last year, according to the world body.