South Korea has resumed blasting propaganda into North Korea with a “sound of freedom” broadcast that touted Samsung’s achievements and reported on North Korean mental health.

South Korea’s National Security Council said it had started measures that “may be unbearable for the North Korean regime” in retaliation after Pyongyang sent hundreds of bags of rubbish over the border attached to balloons.

Among these measures was the resumption of the loudspeaker broadcasts, which were suspended in 2018 when relations between the two countries warmed for a time.

South Korean news site YNA said the speakers were playing a psychological warfare broadcast dubbed “voice of freedom” but did not say where they were located or give full details of the content.

One of the news outlet’s reporters said the broadcast resumed around 5pm local time with the message: “Hello, fellow North Koreans. From now on, we will begin a freedom broadcast that delivers the sound of truth and hope.”

A number of news items then followed, aimed at punching through the North’s tight censorship, which includes restrictions on broadcasts from outside the country.

Among these was the announcement that the South had suspended its 2018 military agreement with the North which was intended to defuse tension.

The broadcast also lauded Samsung’s position as one of the world’s top exporters of smartphones and warned of the regime in the North’s censorship.

“[T]he number of North Korean residents complaining of mental pain is increasing due to the sudden strengthening of crackdowns and censorship on the viewing and distribution of external videos,” YNA cited the broadcast as saying.

The resumption of the broadcasts came after the South warned its northern foe to stop the rubbish balloons, which began in May. On Saturday, about 330 were launched, with about 80 of them landing south of the border, South Korea’s military said.

Among the items contained in the bags attached to the balloons have been animal faeces, toilet paper and rubbish.

The South said the balloons “clearly violate international laws and seriously threaten the safety of our people”.

The North says the rubbish dumping was in response to the use of balloons by activists in South Korea to disseminate of leaflets criticising its regime and flash drives containing K-pop music and Korean dramas.

Seoul did not say how long it will continue with the broadcasts, but experts say they could have serious implications, with previous propaganda tit-for-tats having significant consequences for inter-Korean relations.

“There is a high possibility the resuming of speakers could lead to an armed conflict,” Cheong Seong-chang, director of the Korean peninsula strategy at Sejong Institute, told AFP.

“With the resuming of the speakers, North Korea will not stay put. It is likely that North Korea will resume firing in the West Sea or fire at the balloons if the South sends any again,” Mr Cheong said.

In 2018, during a period of improved inter-Korean relations, the leaders of the two Koreas agreed to “completely cease all hostile acts”, including stopping the leaflets.