No formal warning issued to captains or ship owners, but industry body says they are exercising greater vigilance

British officials believe Russia will try to retaliate for the Royal Marines’ seizure of the oil tanker Smyrtos, prompting UK ship owners to exercise greater vigilance until tensions with Moscow ease.

Military sources said the UK had considered possible responses to the seizure of the vessel carrying Russian crude worth $40m (£30m) to India, and anticipate that the Kremlin will want to hit back.

Keir Starmer has called the firing of warning shots by a Russian warship at a British yacht sailing across the Channel on Tuesday ‘deeply concerning and reckless’.

Russia’s defence ministry said the yacht was on a ‘dangerous course’ and several attempts were made to contact it – a claim disputed by the retired couple onboard the 40ft yacht.

Nosheen Iqbal speaks to the Guardian’s defence and security editor, Dan Sabbagh – watch on YouTube