Yemen's Iran-backed Houthi (Ansarallah) fighters seized a Saudi-flagged tug and two South Korean vessels at the weekend, the insurgents and Seoul officials said on Tuesday (November 19th).
The incident follows a lull in Houthi attacks on Saudi Arabia as one Riyadh official said the kingdom had established an "open channel" with the militia fighters in a bid to end the four-year conflict.
The Houthis acknowledged they had seized three ships, including a Saudi one, in the Red Sea a few miles off Uqban island, west of Houthi-held Sanaa.
Seoul's foreign ministry said a South Korean dredger was being towed by one Korean and one Saudi-flagged tug when they were seized by the Houthis.
It added that a total of 16 crew, two of them South Korean, had been taken to the Red Sea port of Saleef, where they were being held by the Houthis.
"All of our citizens... are healthy and safe," ministry officials said in a statement.
"We are doing our very best for the early release of our citizens."
Seoul has sent the South Korean navy ship Cheonghae, which had been on anti-piracy standby off the coast of Oman, to waters near where the incident took place.
The Saudi-led military coalition backing Yemen's internationally recognised government accused the Houthis of "hijacking" the Rabigh-3, which a global tracking website described as a Saudi-flagged vessel.
The Houthis on Tuesday said the three ships were seized off Uqban island after they entered "territorial waters without prior notice", according to a statement carried by their al-Masirah television channel.
The ships were taken to Saleef, it added, without disclosing the nationalities or number of crew members.