North Korea has accused South Korea of flying drones “filled with heinous slander” into its capital city.

The North Korean foreign ministry said the drones carrying anti-regime propaganda had violated its airspace three times in recent weeks, warning it would respond with “all means of attacks” if the incursions continued.

Citing the North’s foreign ministry, the official Korean Central News Agency reported Friday that the South had sent drones into the Pyongyang airspace on Oct 3, and then again on Wednesday and Thursday this week.

Pyongyang said the alleged incursion was an “irresponsible and dangerous” provocation that could lead to “armed conflict and even war”.

“This incursion into our airspace is a serious crime that violates our sovereignty,” the North’s foreign ministry said. “South Korea has chosen its own destruction. It is hastening its downfall.”

South Korea denied sending the drones and said it would review whether the propaganda leaflets were sent by private organisations.

“We have not done that. I am not aware of the situation,” Kim Yong-hyun, South Korea’s defence minister said on Friday, according to local reports.

It comes as relations between the two Koreas are at one of their lowest points in years, with Kim Jong Un declaring South Korea his country’s “principal enemy” earlier this year.

Despite official efforts to prevent them, South Korean activists have for years flown balloons containing propaganda leaflets and US dollars over the border, a tactic which infuriates Pyongyang.

In response, Pyongyang has sent thousands of balloons filled with rubbish and paper waste into South Korea. Seoul, in turn, broadcast propaganda and K-pop music across the border through loudspeakers.