Just days after the anniversary of the US killing of a top Iranian general in a drone strike in Iraq, Iran itself launched exercises featuring a wide array of domestically produced drones, Iranian media reported.

Iran and the regional forces it backs have increasingly relied in recent years on drones in Yemen, Syria, Iraq and the Strait of Hormuz at the mouth of the Gulf, Reuters reported.

Iran’s armed forces are to test combat drones used as bombers, interceptors and in reconnaissance missions in the two-day exercises in central Semnan province, the semi-official Fars news agency said.

Beyond surveillance, Iranian drones can drop munitions and also carry out a "kamikaze" flight when loaded with explosives and flown into a target, according to a US official who spoke to Reuters.

Iran has developed a large domestic arms industry in the face of international sanctions and embargoes that bar it from importing many weapons.

The exercises coincided with increased tensions between Iran and the United States, two days after the first anniversary of the killing of Iranian general Qassem Soleimani in a US drone strike at Baghdad airport, and two weeks before President-elect Joe Biden takes office. 

Biden aims to revive the nuclear agreement, though diplomacy is expected to be tricky, Reuters reported.

On Monday Iranian forces meanwhile seized a South Korean tanker in the Gulf, and Tehran also announced plans to increase uranium enrichment.

South Korea says it will dispatch a government delegation to Iran “at the earliest possible date” to try to secure the release of the tanker seized by Iran amid tensions over Iranian funds frozen in Seoul because of US sanctions.

According to South Korean media, a Foreign Ministry spokesman made the announcement on Tuesday, a day after the Islamic Revolutionary Guards Corps (IRGC) seized the tanker and detained its crew of 20 near the Strait of Hormuz over pollution violations -- an allegation rejected by the ship's operator.

The spokesman also said that South Korean Deputy Foreign Minister Choi Jong-kun will go ahead with a previously planned trip to Tehran early next week, as Iranian officials seek the release of billions of dollars frozen in South Korean banks.

South Korean News Net reported that the frozen assets stem from oil sales earned before Washington tightened sanctions on Iran following the US withdrawal from a landmark nuclear deal between Tehran and world powers.

In Tehran, an Iranian government spokesman rejected allegations that Iran's seizure of the tanker amounted to hostage taking, the news portal reported.

“If anybody is to be called a hostage taker, it is the South Korean government that has taken our more than $7 billion hostage under a futile pretext,” Ali Rabiei told reporters.

Earlier, the US State Department called for the tanker's immediate release, accusing Iran of threatening “navigational rights and freedoms” in the Persian Gulf in order to “extort the international community into relieving the pressure” of economic sanctions.

Meanwhile, the South Korean Defense Ministry announced that a destroyer carrying members of South Korea's anti-piracy unit arrived in waters near the Strait of Hormuz -- through which 20 percent of all oil traded passes -- and was “carrying out a mission to ensure the safety of our nationals.”