DUBAI (Reuters), – Iran’s maritime state said Saturday that the crews of two Greek tankers seized Friday by Revolutionary Guards had not been held and they were being taken care of onboard.

Two Greek tanks were seized by Iranian forces in the Gulf after Tehran threatened to take “punitive actions” against Athens for the US’s seizure of Iranian oil from an American tanker off Greece’s coast.

According to Iranian Ports and Maritime Organizations, “The crews of the Greek tankers were not arrested and they are all in good health.” The statement was made by state media.

Two vessels were stopped because of unspecified “maritime violation”, according to the body.

Greece claimed that an Iranian Navy helicopter crashed into the Greek-flagged ship Delta Poseidon, in international waters. It also took its crew hostage. Without naming the vessel, it claimed that a similar incident occurred on another Greek flagged ship near Iran. Athens claimed both acts were in violation of international law.

The European Union sanctioned Iranian-flagged Pegas was confiscated by Greek authorities last month. Reuters reported that on Thursday, the United States took possession of Iranian oil cargo aboard.

However, the Pegas and Russian crew members were released later. The seizure exacerbated tensions while Iran and international powers attempt to revive an 2015 nuclear agreement.

Separately Nour News, an Iranian state security organization, stated: “Iran won’t remain passive in face of any threat its interests. Testing Iran’s will will be a strategic mistake that will result in heavy costs for both the United States, its entourage, and the United States.”

Saeed Khatibzadeh is the spokesperson for Iran’s Foreign Ministry. He tweeted, “Our ties should not be compromised by deeply shortsighted mistakes, including highway theft on command from a third party.”

Two weeks after British forces had detained an Iranian ship near Gibraltar for violating European Union sanctions, Iran took control of a British tanker in Iran. The vessels were both later released.