North Korea has sent hundreds more trash-filled balloons across the border in a fresh blitz, Seoul’s military said Sunday, as the tit-for-tat balloon barrages between the two neighbours accelerates.

Since the latest blitz began late Saturday, Pyongyang has sent an estimated 330 balloons carrying bags of trash into the South, Seoul’s military said.

“So far, about 80 have fallen in our area and nothing is currently being identified in the air,” the Joint Chiefs of Staff said Sunday in a statement.

“Our analysis shows there were no substances that were harmful to safety,” it said, adding that the latest batch of balloons contained waste paper and plastic.

The Seoul city government, as well as officials in surrounding Gyeonggi province, sent out a text alert to residents on Saturday, warning about the balloons.

“North Korea is making another low-class provocation with trash balloons against our civilian areas,” wrote Seoul mayor Oh Se-hoon in a Facebook post.

In recent weeks, activists in the South have floated dozens of balloons bearing K-pop, dollar bills and anti-Kim Jong Un propaganda northwards, infuriating Pyongyang which has retaliated in kind.

Pyongyang sent nearly a thousand balloons carrying cigarette butts and toilet paper across the border early June, before calling off its campaign, but it restarted Saturday in response to new launches last week by the activists, which Seoul’s government is legally powerless to prevent.

A South Korean group called “Fighters for Free North Korea” said it had sent 10 balloons with thumb drives containing K-pop music and 200,000 leaflets condemning Kim’s rule this week.