A PANAMA registered tanker suspected of violating UN sanctioned by selling oil to North Korea,  has been detained in a South Korean port.

The Koti ship, of 5,100 tons, has been held in  Pyeongtaek-Dangjin (west of the country) since at least December 21.

Most of its crew are  Chinese and Burmese nationality, according to local news agency Yonhap, citing maritime authorities.

It is the second case of a ship investigated by the South Korean authorities for supplying crude oil to the North Korean regime on the high seas. On Friday, Dec,27 the Government of Seoul announced that it had seized a ship with the flag of Hong Kong.

The Winmore Lighthouse was detained on arrival at the port of Yeosu (south) on November 24, after allegedly transferring some 600 tonnes of refined oil to a North Korean ship on October 19.

UN resolution 2375, unanimously approved last September following the latest and most powerful nuclear test of the Kim Jong-un regime, limited the supply of oil to North Korea as of October 1, 2017, and prohibits the export of petroleum condensate.

The insistent North Korean weapons tests, including the launching of ballistic missiles, led the UN to tighten its sanctions on December 22, further limiting access to oil products.

After announcing that the Hong Kong ship had been retained by Seoul authorities, US President Donald Trump lashed out at China.

"Caught red-handed - very disappointed that China is allowing oil to go to North Korea." There will never be a friendly solution to the problem of North Korea if this continues to happen, "said Trump  on Twitter

The Chinese Government denied that its country has allowed any such act.