At least four civilians have been killed and 14 others wounded in an explosion in the eastern Afghan province of Khost, local officials say.

Provincial police chief Faizullah Khairat said the blast occurred at around midday on September 17 at a marketplace in the provinceial capital, Khost.

Khairat said the blast was caused by a "remote-controlled bomb."

A number of those injured were said to be in critical condition, according to Mubarez Zadran, a spokesman for the provincial governor.

No group has claimed responsibility for the attack, but the volatile province bordering Pakistan has been contested by the Taliban.

As the holy Muslim month of Ramadan began on May 27, a Taliban car bomber targeted an Afghan militia group in Khost, leaving 13 people dead.

A U.S.-led invasion drove the Taliban from power in Afghanistan after the September 11, 2001, terrorist attacks in the United States -- carried out by Al-Qaeda, whose leaders were harbored by the Taliban in Afghanistan.

But the government is struggling to beat back insurgents in the wake of the exit of most NATO forces in 2014.

A U.S. report found earlier this year that the Taliban controls or contests control of about 40 percent of the country, and security forces are also fighting against militants affiliated with IS.

With reporting by AFP and dpa