A MH-60S Sea Hawk helicopter from the "Nightdippers" of Helicopter Sea Combat Squadron 5 lifts off from the flight deck of the aircraft carrier USS Abraham Lincoln (CVN 72) as it transits the Strait of Hormuz. Picture: Stephanie Contreras/U.S. Navy/Handout via Reuters

London - Britain plans to send two warships to protect vessels in the Strait of Hormuz, amid tension with Iran, Defence Minister Ben Wallace said late Saturday.

Wallace said Britain will deploy the HMS Montrose frigate and the HMS Defender destroyer in the strait, a strategically important shipping route in the Gulf region.

He urged all sides to "engage to de-escalate the situation," amid heightened tension following the US airstrike that killed Qassem Soleimani, the commander of Iran's elite Quds Force.

Wallace said he spoke to US Defence Secretary Mark Esper on Friday, adding that US forces had been "repeatedly attacked by Iranian-backed militia" in Iraq in recent months.

"General Soleimani has been at the heart of the use of proxies to undermine neighbouring sovereign nations and target Iran's enemies," he said in a statement.

"Under international law the United States is entitled to defend itself against those posing an imminent threat to their citizens," Wallace said.

The two British warships were deployed in the strait last year after Iranian forces seized a British-flagged oil tanker.