SEOUL (REUTERS, AFP) - South Korea will release three North Koreans who crossed the maritime border aboard a fishing vessel at the weekend, Seoul's Unification Ministry said on Monday (July 29).

"All of the three crew members, as well as the wooden vessel, will be returned to the North," the ministry told reporters in Seoul.

The boat and three crew had set off, a ministry official told AFP.

North Korean fishing boats often breach the inter-Korean maritime frontier or go adrift towards the South.

However, South Korean authorities towed the ship that crossed the border last Saturday because a white towel was tied to its mast, a potential sign that those on board might want to defect, officials said.

The North Koreans on the vessel said during questioning that they had gone off course by mistake and wanted to return home.

South Korea notified Pyongyang that the crew members had willingly left a South Korean port for the North, the ministry in charge of inter-Korean affairs said in a statement.

The incident comes after a North Korean fishing boat crossed the intensely monitored border undetected in June and sailed into a South Korean port before it was identified.

Two of the four crew members said they wanted to defect and the other two were sent back to the North.

A South Korean general was sacked over the lapse in border security.