The British government has imposed sanctions on five Russian banks and three oligarchs.

She was reacting to the speech of Russian President Putin and the invasion of the first troops in eastern Ukraine.

Prime Minister Boris Johnson said on Tuesday that a "general invasion of Ukraine by nearly 200,000 troops" should now be expected from Russia.

Putin is making a big mistake, Johnson warned.

Russia will become a pariah state if the Kremlin continues.

The kingdom on Tuesday imposed sanctions on five financial institutions particularly close to the Kremlin, namely Rossiya Bank, IS Bank, General Bank, Promsvyazbank and Black Sea Bank.

Promsvyazbank is behind 77 percent of state contracts signed by the Russian Defense Ministry, Johnson said.

In addition, three well-known oligarchs are placed on the sanctions list, namely oil oligarch Gennady Timchenko, billionaire Boris Rotenberg, who is closely linked to Gazprom, and his nephew, construction magnate Igor Rotenberg.

Their assets in Britain will be frozen and they will no longer be allowed to enter the kingdom.

Russia's economy is said to be weakened

"The sanctions we are imposing today are very tough," Johnson said in Parliament in London.

"But we have prepared much tougher sanctions and will not hesitate to use them," he added.

Various Labor MPs and individual Tory MPs urged Johnson to take tougher action and sanctions on more Russian-linked oligarchs.

As a further measure, Johnson announced that he would cut off Russian companies from the British capital market.

"We stop Russian companies from raising funds in pounds sterling or dollars in our market." That will "cause real economic damage where it's needed," Johnson said.

In addition, the government will step up action against money laundering and undeclared assets from dubious sources.

London has long been viewed in intelligence circles as the western capital of money laundering for Russian oligarchs.

Johnson heard from the Labor opposition that his party had accepted donations from wealthy Russians.

Johnson later emphasized that there should be no general "Russophobia".

There should be no general discrimination against Russians just because of their nationality.

Several thousand wealthy Russians have settled in Britain since the 1990s.

Several thousand millionaires came through so-called "golden visas" that were given to rich investors.