Iran's Islamic Revolutionary Guards Corps (IRGC) seized a South Korean-flagged tanker transporting thousands of tons of ethanol in the Persian Gulf and detained its crew, The Telegraph and Reuters reported Tuesday, citing state news agencies FARS and IRIB News.

"The Iranian regime continues to threaten navigational rights and freedoms in the Persian Gulf as part of a clear attempt to extort the international community into relieving pressure of sanctions," the report said.

The act is a provocation of fresh confrontations with the West as Iran also said it has resumed its uranium enrichment program to up to 20 percent in the nation's biggest violation yet of its historic nuclear agreement with Western powers, a government spokesperson told state-run Mehr News on Monday.

Seoul confirmed the seizure of a South Korean chemical vessel by Iranian Revolutionary Guards in the waters off Oman and demanded its immediate release. South Korea said 20 crew members were on board, five of whom are South Koreans.

Multiple Iranian media news agencies said the Guards captured the tanker for polluting the Gulf with chemicals. But this was denied by South Korea's foreign ministry. The U.S. Department of State demanded Iran to release the seized vessel immediately.

The enhanced uranium program puts the Islamic Republic a technical step away from attaining a 90 percent enrichment, the level required to manufacture a nuclear bomb. Prior to the announcement, the country was enriching uranium at around 5 percent, in clear breach of the nuclear accord but at a much lower level.

Tehran is also in dispute with Seoul, which has for months refused to release Iran's $7 billion oil revenues currently held in its banks, citing U.S.-led sanctions.

The U.S. reimplemented sanctions on Iran in 2018 after Washington backed out of Tehran's 2015 nuclear agreement with six world powers. Under that accord, Iran agreed to reduce its nuclear activity in exchange for the lifting of sanctions.