The prime minister has come under pressure to act against Britain's secretive offshore industry at June's G8 summit, as leaked evidence continued to mount that politicians and tycoons from all over the world have used the British Virgin Islands to hide funds.

The premier of Georgia, Bidzina Ivanishvili, was the latest to be named, along with prominent Pakistani, Indian, Thai and Indonesian figures – while there was fresh evidence of Britons acting as front directors for companies based in offshore havens such as the BVI.

A senior Liberal Democrat figure said the leaks showed the secret haven of the BVI "stains the face of Britain", as anti-corruption campaigners called for action.

Lord Oakeshott, the Lib Dem peer and a former Treasury spokesman, said: "How can David Cameron keep a straight face calling for the G8 to make big business pay tax when we let the BVI use British law and British protection to suck in billions in dirty money?"

He asked: "How much British aid paid to corrupt countries like Pakistan ends up behind a BVI brass plate?"

Despite mounting evidence that British sham directors are selling their names as fronts for offshore secrecy, the UK's Department for Business, Innovation and Skills (BIS) signalled that politicians are reluctant to move against them.

A report on the sham directors scandal has already been sent to ministers by the BIS deputy head of corporate governance, Jo Shanmugalingam. This followed a Guardian-BBC investigation last year into the leaked data which revealed that two dozen Britons, giving obscure offshore addresses, were purporting to control thousands of companies.

The latest example, which emerged on Thursday, is of a "general builder", Kevin Gaitely. He gives an address in south London and is registered as the director of Tamalaris Consolidated, a company blacklisted by the UK and US as a front for Iran. He is recorded as a director of a variety of other UK and BVI companies.

Ministers insist they are not ready to act. The BIS issued a statement on Thursday night saying: "The vast majority of companies and directors do comply with the law and they should not be unfairly burdened, so we will focus our attention on those who deliberately seek to break the law."

It is not illegal as such for Britons to rent out their names on behalf of offshore companies, so the BIS statement appears to be a recipe for inaction.

Meanwhile MPs criticised tax avoidance in Pakistan in a report issued on Thursday by the UK Commons committee on overseas aid. It said: "We cannot expect people in the UK to pay taxes to improve education and health in Pakistan if the Pakistani elite does not pay meaningful amounts of income tax."

Robert Palmer of the campaign group Global Witness repeated the call for Cameron to act, saying: "The massive cache of leaked documents demonstrates how hidden ownership of shell companies facilitates corruption, tax dodging and other crimes."

He said: "The time to deal with this issue is now. Given that he has pledged to tackle these secretive shell companies at this year's G8 summit in Northern Ireland, he and his fellow leaders must commit to publishing information on the people who ultimately control and own companies."

The names of thousands of owners of secret offshore companies are currently being published by the Washington-based International Consortium of Investigative Journalists (ICIJ), in collaboration with the Guardian and other international media.

This follows the leak to ICIJ of a hard drive containing 200GB of internal files of offshore incorporation agencies in the BVI, Singapore and the Cook Islands.

A spokesman for the Georgian prime minister, who had set up a BVI company called Bosherston Overseas Corp, said he had done everything in accordance with the law: "For the reporting period of 2011-12, prime minister Ivanishvili had no interest in the company … and therefore there was no obligation to report it in his [financial] declaration."

In India, an MP from the ruling Congress party, Gaddam Vivekanand, said after an offshore company, Belrose Universal, was revealed to have been listed in his name: "I do not remember being involved with such a company and have no connection with it.''

A spokeswoman for Stephen Riady, who heads one of Indonesia's richest families, said there was "nothing illegal or improper in protecting the privacy of one's own information" after the leaked files revealed that his family's Lippo Group conglomerate controlled a number of offshore entities.

The incorporation firm, TrustNet, refers to them as "Client A", noting "client does not want to be seen dealing offshore". Their agent, Gary Phair, instructed TrustNet staff to "delete any reference to 'C/- [Care of] Lippo".

Thai MP Nalinee Taveesin, currently an official trade representative and previously blacklisted by the US for allegedly helping Robert Mugabe avoid sanctions, denied knowing about the offshore company Hall Kingston International, listed in her name.

Her secretary said: "The information about her being [a company] shareholder is incorrect."

In Pakistan, Moonis Elahi, a politician from a prominent Punjab dynasty who was acquitted in a Pakistan court in 2011 of receiving payments in a corruption scandal, said he did not own offshore company Olive Grove Assets, listed to his name at the family residence in Lahore. He did not state whether he had previously owned the firm.