An American national has been taken into custody by South Korean military authorities after being detained trying to swim to North Korea.

The man, who has not been named, was arrested by South Korean Marine sentries shortly before midnight on Tuesday as he attempted to swim across the River Han where it forms the border with North Korea at Gimpo.

In his early 30s and identified by Yonhap News as an American national of Arabic descent, the man was handed over to South Korean intelligence officers for questioning.

“I was trying to go to North Korea in order to meet with supreme leader Kim Jong-un,” Yonhap quoted the man as telling his interrogators.

The man was defying US government advice against travelling to North Korea, advice that has become firmer in the aftermath of the arrest of three US nationals in recent months, reports The Telegraph.

As recently as Sunday, Matthew Miller, from Bakersfied in California, was sentenced to six years in a North Korean prison after being found guilty of “hostile acts” against the regime.

The details of the charges have not been announced by the court in Pyongyang, although 24-year-old Miller reportedly tore up his visa and demanded asylum in the North shortly after arriving in April.

Miller is one of three US nationals presently held in North Korea.

Kenneth Bae was found guilty in April 2013 of “hostile acts against the republic” and attempting to overthrow the government. Sentenced to 15 years hard labour, 46-year-old Bae has been hospitalized for treatment for diabetes, high blood pressure and back pains and his family have appealed for his release.

Relatives of Jeffrey Fowle, 56, have also called on Pyongyang to free the Ohio native, who was detained for leaving a bible in the hotel where he had been staying. Fowle is awaiting trial.

Analysts say North Korea is using the detainees to force the US to the bargaining table to try to win their freedom.

Senior US diplomats and even Jimmy Carter, the former US president, have made humanitarian trips to Pyongyang in the past to secure the freedom of US detainees.

Such meetings are used as domestic propaganda by the regime, to demonstrate that North Korea forced its powerful enemy to give in to its demands.