Investors who have stashed money in tax havens in Europe and the Channel Islands are to be asked to give themselves up to HM Revenue & Customs in exchange for reduced penalties, The Sunday Times can reveal.

The move is designed to flush out those with secret savings in offshore bank accounts ahead of legal moves by the Revenue to force 117 foreign and UK institutions to disclose customers’ details.

It raised £400m last year after taxpayers with money in offshore accounts operated by five high-street banks — Barclays, HBOS, Lloyds TSB, HSBC and Royal Bank of Scotland — were offered leniency in return for voluntary disclosure. Most account holders with those banks who took up the offer paid 10% of outstanding tax, rather than 100%. The new “amnesty” will apply to all offshore account holders.

The latest move follows the discovery of details of 300 British citizens who have bank accounts at LGT, a bank in the principality of Liechtenstein, that were previously unknown to UK tax authorities. A former employee of LGT disclosed the information to the Revenue and was paid a “reward” of about €100,000 (£79,000).

In an exclusive interview with The Sunday Times, Dave Hartnett, the Revenue’s acting chairman, said the reduced penalty system would be more complex than the first, but there would be a “structure to support those who want to go on the straight and narrow”.

He said he would push for jail terms for those who did not come forward. The deal may not apply to those who ignored the first offer. “Why should we give you a second chance to have a good deal?” he said.

He added: “We want to clean this up. We are saying to individuals if they come forward before we write to them, we would probably regard that as voluntary and they will tend to walk away with more money than those who do not come forward.

“Some people will go to jail — I have no doubt about that, for example where they have lied to us during a previous investigation. We do not tolerate that at all.” The Revenue is also targeting 20,000 customers who registered for the first scheme but then failed to come forward with their details. About 64,000 people registered ahead of the deadline in November last year, but only 45,000 made a subsequent disclosure.

Hartnett said: “We think that some of them lost their nerve and are now a priority for us."

The Revenue is poised to prosecute up to 10 tax evaders discovered as a result of the investigation.

British citizens are thought to have salted away up to £2 billion in banks across the secretive principality of Liechtenstein, with hundreds of millions in unpaid income tax and capital gains tax owed to the UK government.

The Revenue is now pursuing another 15 Liechtenstein banks for money thought to be buried in the principality. It is also seeking orders to compel an initial tranche of 25 foreign banks to produce details of accounts held by Britons in the Channel and Virgin islands, Panama and Monaco.

Hartnett said: “If we secure co-operation from Liechtenstein banks this might be completed in two to four years. We will go on until we get access.”

The great offshore riddle