North Korea fired artillery rounds near its disputed sea boundary with South Korea on Friday in violation of a fragile 2018 military agreement, officials in the south have said.

South Korea’s Joint Chiefs of Staff said North Korea fired 200 rounds in the waters north of their disputed western sea boundary, and they would take carry out similar drills in response.

People living on the frontline island of Yeonpyeong said the South Korean military has asked them to evacuate because it plans to launch maritime firing drills on Friday.

The sea boundary has been the site of several bloody inter-Korean sea battles since 1999. North Korea also launched artillery strikes on Yeonpyeong island, killing four South Koreans, in 2010.

The 2018 agreement requires both countries to halt live-fire exercises and aerial surveillance in no-fly and buffer zones established along their border, but the deal is in danger of collapsing amid bickering since the North’s first military spy satellite launch in November.

South Korea accused North Korea of restoring frontline guard posts that it had dismantled under the 2018 deal after South Korea resumed aerial surveillance in protest of the satellite launch.

Earlier on Friday, North Korea’s state media said leader Kim Jong Un ordered authorities to increase production of mobile launch vehicles for missiles because the country faces a looming military showdown with its enemies.

The official Korean Central News Agency said Mr Kim made the comments during a visit to a factory that produces transport erector launchers (TELs) without saying when he went or where the factory is.

TELs are mobile launch vehicles which give North Korea the ability to move missiles around its territory, making it more difficult for its adversaries to detect launches in advance. Some South Korean experts have estimated that North Korea has about 100-200 such vehicles.

Mr Kim said the factory’s role is “very important” in bolstering North Korea’s national defence “given the prevailing grave situation that requires the country to be more firmly prepared for a military showdown with the enemy,” KCNA reported.

In a key ruling party meeting last week, Mr Kim vowed to expand the country’s nuclear arsenal, launch three additional military spy satellites and take other steps to build up the military this year to acquire “overwhelming” war readiness to cope with what he called US-led confrontation.

He cited the expansion of US-South Korean military drills that sometimes involve US long-range bombers and a nuclear-armed submarine.