Britain has ratcheted up pressure on Russia by announcing sanctions against 65 more businesses and individuals as the war in Ukraine entered its second month, but ministers were urged to go further and crack down on gas imports and oligarchs hiding their wealth in trust funds. Among those who had their assets frozen were six banks and a defence company that produces drones, as well as the Wagner Group, which the UK said had reportedly been tasked with assassinating the Ukrainian president, Volodymyr Zelenskiy. The “mayor” of Melitopol, a region in south-eastern Ukraine currently under Russian military occupation, also faced sanctions for “collaboration” with the invading forces, in the first announcement of its kind. Other individuals targeted included the billionaire oil tycoon Eugene Shvidler, who has close links to Roman Abramovich; Herman Gref, the chief executive of Russia’s largest bank, Sberbank; and Polina Kovaleva, the Russian foreign minister Sergei Lavrov’s stepdaughter, who reportedly owns a £4m house in London. The foreign secretary, Liz Truss, said all were “complicit in the murder of innocent civilians” and should “pay the price”. She added: “Putin should be under no illusions – we are united with our allies and will keep tightening the screw on the Russian economy to help ensure he fails in Ukraine. There will be no let-up.” The sanctions, which were also imposed on Alrosa, the world’s largest diamond producer, will ban all those targeted from travelling to or from the UK and freezes their UK-based assets indefinitely. Despite four weeks passing since Russia’s president, Vladimir Putin, ordered the invasion of Ukraine, Truss is understood to want to keep tightening the vice around those with links to the Kremlin. The move came while she and the prime minister, Boris Johnson, joined Nato and G7 summits in Brussels. While the total number of people and businesses facing sanctions is now more than 1,000, government insiders have privately admitted the UK initially moved too slowly to stop some oligarchs transferring their wealth and assets out of the country before they were targeted. David Lammy, the shadow foreign secretary, said ministers were playing catch-up and called for them to speedily implement more sanctions. He said: “There are still gaps and loopholes in the government’s sanctions: trusts not fully covered, banks not yet designated, ownership thresholds that are too high. And we need to ensure effective enforcement, including across the UK’s overseas territories and crown dependencies. “Labour welcomes the measures announced today, but we will keep the pressure up to make sure sanctions against Putin and his interests are comprehensive and watertight.” Ofgem, the UK’s energy regulator, has also come under pressure from the Liberal Democrats, who have called for Russian oil and gas giant Gazprom to be banned from supplying energy to UK businesses by revoking its supply licence and effectively nationalising it by placing it into “special administration”. Ed Davey, the party’s leader, said hospitals, schools and councils could “inadvertently be helping expand Putin’s war chest if they were locked into a long-term contract with Gazprom”. The Guardian also revealed on Wednesday that Alisher Usmanov, once said to be the UK’s richest person, had claimed to have placed hundreds of millions of pounds of his assets into an irrevocable trust, potentially leaving them outside the sanctions regime established by western governments.