South Korean officials said on Sunday that they had seized a Panama-flagged ship suspected of carrying illegal oil shipments to North Korea in breach of international sanctions, just days after announcing that a first vessel had been impounded in November.

The vessel, the KOTI, was seized as the UN strengthens efforts to shut down the flow of oil to the North in response to Pyongyang's ongoing nuclear and ballistic missile tests.

The boat was detained at Pyeongtaek-Dangjin, a west coast port south of Incheon.

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A marine official confirmed the seizure, which he said occurred "recently."

The KOTI was due to arrive at the port on December 19, according to VesselFinder Ltd., a tracking service provider. After a government meeting on December 21, the ship was detained.

"The vessel is under inspection for alleged ties with North Korea," a government official said, according to the Yonhap News Agency.

The ship can carry 5,100 tons of oil and has a crew primarily from China and Myanmar, according to Yonhap. The agency also reported that officials from South Korea's intelligence and customs agencies were conducting a joint probe of the vessel and interviewing the crew members.

A South Korean Foreign Ministry spokesman confirmed the investigation but declined to give details.

"The government has been in close consultations with related countries and ministries to thoroughly implement the sanctions by the UN Security Council," the spokesman said.

Doubts about China and Russia

On Friday, South Korea revealed that it seized a Hong Kong-flagged vessel dubbed Lighthouse Winmore (pictured at top) late last month. The ship was reportedly carrying 600 tons of oil bound for transfer to a North Korean vessel — the Sam Jong 2.

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The UN Security Council recently passed a unanimous resolution imposing tough new sanctions on the North for its recent intercontinental ballistic missile test.

The US has also called on the Security Council to blacklist 10 shipsfor transporting banned items from North Korea.

The Lighthouse Winmore is one of the 10 ships on the proposed blacklist, but the KOTI is not.

On Thursday, China blocked a US attempt at the UN to blacklist six foreign-flagged ships, according to a UN Security Council diplomat.

China's Foreign Ministry maintained that Beijing was fully and strictly implementing all Security Council resolutions.

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"At the same time, any measures taken by the Security Council must have a basis in conclusive and actual proof," according to a brief statement. "China will continue to participate in the work of the relevant Security Council sanctions committee on this principle," though it did not elaborate.

Germany's warning

German Foreign Minister Sigmar Gabriel has warned the global community against a failure to act over North Korea's nuclear weapons program.

"If North Korea were to acquire nuclear weapons and the rest of the world just looked on, that would be terribly dangerous," Gabriel told the Funke media group in remarks published Sunday. "In that case, others will follow their example."

A military solution would, however, "cost an inconceivable number of human lives," Gabriel added.

"At the end of the day, only the United States and Russia, supported by China, can stop the proliferation of nuclear weapons," the foreign minister asserted.

Both China and Russia are suspected of violating the UN sanctions regime with oil deliveries to North Korea in recent months.

bik/tj (Reuters, AFP, dpa)