The United Kingdom on Thursday stated that a BP oil tanker sailing under the Isle of Man flag was almost denied passage through the Strait of Hormuz between the Persian Gulf and the Gulf of Oman by thee Iranian vessels. The tanker was only able able to continue its journey after a British warship intervened, with its crew sending “verbal warnings” to the Iranian ships.

The UK government told Iran to “de-escalate the situation in the region,” but Iran’s Foreign Minister denied the reports. Last week, Iran threatened to capture a British oil tanker unless the United Kingdom would release an Iranian tanker that was recently seized in Gibraltar by UK Marines.

Tensions between Iran and the West have surged in recent weeks. Iran recently violated the 2015 Iran nuclear deal by exceeding the amount of low-enriched uranium it is allowed to store, and by starting to enrich uranium at higher levels than allowed under the agreement. The Iranian regime has said that it is violating the Iran deal as a response to US sanctions, and has urged the UK and other European signatories to take urgent steps to significantly reduce the impact of these sanctions. United States President Donald Trump on Wednesday warned that the sanctions on Iran would be “substantially” increased.

Read more: Britain says Iran attempted to block its oil tanker