The U.S. Embassy in Afghanistan issued an emergency message for U.S. citizens in the country's capital Monday, saying it had received "credible reports of an imminent attack" within the next 48 hours.

The statement said that there were no details available regarding the attack's time, target or method. However, it urged Americans in Kabul to "exercise extreme caution if moving around the city."

Earlier this month, the State Department issued an updated travel warning for Afghanistan in the wake of the terror attacks in Paris. That warning advised Americans not to travel to Afghanistan, citing the "extremely unstable" security situation.

Taliban militants have stepped up attacks on Afghan government facilities in recent months. On Saturday, a suicide bomber targeted a member of the country's election commission in Kabul, killing the official's bodyguard and wounding his driver. 

In September, Taliban fighters briefly overran Afghan forces to take control of the northern city of Kunduz. Bombings, especially roadside bombs, have also been a major threat to both Afghan security forces and civilians across the country.

The Associated Press contributed to this report.