LONDON — British Prime Minister Boris Johnson has said the West made a "terrible mistake" and let President Vladimir Putin "get away" with annexing Crimea in 2014.

Writing in the Telegraph, Johnson said ending the West's dependence on Russian oil and gas was vital to "end the bullying" from the Kremlin.

It comes as the foreign secretary is expected to announce further sanctions.

About 100 more people are likely to be sanctioned under newly-passed legislation, the BBC has learned.

In his article in the Telegraph, Johnson said: "When Putin invaded Ukraine the first time round, in 2014, the West made a terrible mistake. The Russian leader had committed an act of violent aggression and taken a huge chunk out of a sovereign country - and we let him get away with it."

Crimea, in the south, was annexed by Russia from Ukraine in 2014 and is home to a sizeable Russian military presence.

Johnson said the only way to halt President Putin's "continuous blackmail" was by ending Western countries' dependence on Russian oil and gas - a process that would be "painful".

He also said his promised Energy Security Strategy for the UK would "double down" on wind energy, exploit solar power and make a "series of big new bets" on nuclear energy. Further drilling in the North Sea was one suggestion he made.

The UK is to phase out Russian oil imports by the end of 2022.

A decision by the government to talk to Saudi Arabia about measures to bring down the cost of energy has been criticised by many MPs after the country executed 81 people at the weekend.

Since Russia invaded Ukraine last month, a growing number of Russians have been sanctioned by the UK. Most recently, 386 Russian MPs who voted to recognise two rebel-held areas of eastern Ukraine as independent have been hit by asset freezes and UK travel bans.

The fast-tracked Economic Crime Bill, passed in the early hours of Tuesday, will now allow the UK to automatically sanction those who have had their assets already frozen by the EU, US or Canada.

This will potentially open the door to hundreds more individual sanctions.

Foreign Secretary Liz Truss is likely to announce new sanctions on Tuesday on more than 100 individuals with links to President Putin's regime, the BBC understands.

Speaking to BBC's Hardtalk, senior Conservative and chair of the Defence Select Committee Tobias Ellwood said sanctions on Russia would lead members of the Russian elite and generals to "recognise there is no future for Russia" and Putin would "eventually go".

However, Ellwood warned that "until then, he will cause absolute carnage in Ukraine and beyond unless we stand up to him". — BBC