South Korean authorities have detained a group of North Koreans that crossed the maritime border in the West Sea on a fishing boat two weeks ago for questioning, a senior official in Seoul said Thursday.

“We were tracking their movements well before the group approached the Northern Limit Line,” the official said, referring to the maritime border. “Authorities are looking into the motive as per protocol.”

The official, however, did not say how many North Koreans had crossed, though they are believed to be a group of families, including children -- a total of no more than 10 people. They said they did not drift and are detained at a military base, the official added, without elaborating.

The latest crossings come as the two Koreas are still at odds over resuming talks for denuclearizing North Korea, the last of which took place in October 2019 between the North and the US. The negotiation fell apart because Pyongyang wanted to ease sanctions meant to curb its nuclear and missile programs while Washington wanted proof of disarmament before sanctions relief.

The COVID-19 pandemic, which gripped the world in early 2020 and led to Pyongyang’s border shutdowns, prompted a drop in North Korean defections in that year, when the figure fell to 229 from a little over 1,000 in 2019. The latest government data puts the number for this year at 34 as of March.