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.

“Seizing the Smyrtos was in the works for a long period. They had gone through the risks, and expectation is Russia will try to retaliate,” said a naval insider. “If they do so, it could be globally. They are likely to take their time and pick their moment.”

No formal warning has been issued to British captains and ship owners, but the UK Chamber of Shipping, which represents the industry, said there was an understanding that there could be the risk of a Russian tit-for-tat action.

“We are aware of the increased risk and owners assess the risk for themselves,” said a spokesperson. “From an industry perspective, a greater vigilance is more prevalent, given the events of the last few days.”

The Smyrtos was seized in the small hours of Sunday on the orders of the British prime minister, Keir Starmer, as it sailed 25 miles (40km) south of the Isle of Wight. Its Indian captain has been charged with breaching UK sanctions on Russia.

On Tuesday, sailors on a Russian frigate, the Admiral Grigorovich, fired warning shots near a British yacht in the Channel. The pleasure boat, which was on its way to the French port of Cherbourg, had come close to the warship, though the couple on board said they had already taken evasive action when the shots were fired.

The Ministry of Defence did not think the incident had been a retaliation, but it demonstrates heightened Russian nervousness as tensions between London and Moscow deepen as a result of the UK’s support for Ukraine.

British-flagged tankers have been seized in tit-for-tat disputes in the past. Iran’s Islamic Revolutionary Guard Corps held the Stena Impero in the strait of Hormuz for two months in 2019.

That incident came after the Royal Marines had detained an Iranian oil tanker, Grace 1, in Gibraltar. It too was released after a couple of months.

The detention of the Smyrtos marks the first time that British forces have seized a Russia-linked oil tanker, and comes as the UK and Europe seeks to put pressure on Moscow’s shadow fleet of about 600 vessels, which are responsible for transporting half its crude oil exports, a key source of revenue to fund the continuing war in Ukraine.

Shadow fleet vessels are often old, falsely or not legally flagged, operating at poor environmental and safety standards. The UK says it captured the Smyrtos, which had been monitored for several days, because it was falsely registered under the flag of Cameroon, and therefore legally stateless.

The Department for Transport, which is responsible for issuing security notices to ship owners, said it was in constant contact with the industry to provide the latest advice. It does not comment on the details of such advice, sources said.