The first military talks between North and South Korea in more than three years have ended in stalemate, with the rivals failing to narrow their differences on how to ease animosity after two shooting incidents last week.

Generals from both sides met on Wednesday at Panmunjom, the “truce village” that straddles the heavily fortified border dividing the peninsula since the end of the 1950-53 Korean war.

During the meeting, North Korea repeated its demands that its neighbour ban activists from dropping leaflets and media outlets from publishing articles critical of Pyongyang, a South Korean ministry spokesman, Kim Min-seok said. South Korean delegates said they could not do so because the country was a liberal democracy, he said.

The two sides were also at odds over the sea boundary, drawn unilaterally by the US-led UN command at the end of the 1950-53 Korean war without North Korea’s consent, Kim said.

North Korea’s leader, Kim Jong-un, reappeared this week after more than 40 days out of the public eye. State media coverage of his recent, but undated, visit to a residential area and energy research complex in Pyongyang were designed to end rumours of political instability. It appears that Kim, 31, who was pictured using a walking stick, had been recuperating after treatment for an unspecified leg condition or injury.

Pyongyang takes exception to the longstanding practice of floating balloons across the demilitarised zone to deliver anti-regime propaganda. It warned that political talks scheduled for next month could be cancelled if Seoul allowed activists to continue their balloon campaign.

While South Korea has urged campaigners not to inflame tensions, it said it had no legal means of preventing the balloon protests.

North Korean soldiers opened fire on the balloons after they were released last Friday, with some of the bullets landing on the southern side of the border. South Korean troops responded with gunfire, but there were no casualties and the exchange did not escalate.

There had been a similar exchange in the week after a North Korean patrol boat crossed the countries’ disputed maritime border in the Yellow Sea.

Wednesday’s talks had raised hopes of a thaw in inter-Korean ties as the neighbours prepare to meet to discuss possible reunions among families divided by the civil war and sanctions Seoul imposed after North Koreaattacked one of its frontline islands in November 2010.

The agreement to hold those talks came after three high-ranking North Korean officials, including Hwang Pyong-so, believed to be Kim’s second-in-command, made a surprise visit to Seoul after attending the closing ceremony of the Asian Games in nearby Incheon this month.

North and South Korea last held working-level military talks in February 2011 but have not held general-level talks, in which each country is represented by two-star generals, since December 2007, Yonhap said.