London: Trouble lay ahead for at least 500,000 people in UK who have stashed their black money in offshore accounts in Switzerland, the Channel Islands and the Caribbean.

According to a report in a news daily, inspectors at Her Majesty's Revenue and Customs (HMRC) department have been "genuinely surprised" by how many middle-class people have secreted funds in havens ranging from Switzerland to the Channel Islands and the Caribbean.

"This is not just about the very wealthy -- we've even found chip shop owners, taxi drivers and landladies from Blackpool with offshore accounts," an official of HMRC said.

"We are not out to victimise these people, but we are determined to ensure we receive what we are owed," he said.

HMRC is confident the crackdown will raise billions of pounds in unpaid tax, interest and penalties.

The agency is creating a directorate to focus on offshore accounts as part of nearly 1 billion pound campaign pledged by the coalition to combat tax cheats.

It is using a new IT system that analyses data on individuals' pay and lifestyle to flag up potential tax dodgers. The system looks for anomalies between where people live, their financial assets and how much tax they pay.

The identities of the 500,000 people with offshore accounts have been obtained through enforced data sharing with banks and from whistle-blowers. HMRC obtained the names of
7,000 British customers of HSBC who bank in Geneva from Herve Falciani, a disgruntled member of the bank's staff.

The accounts of Britons named on what has become known as "the Falciani list" hold assets of about 13 billion pounds and HMRC is confident it will raise tens of millions of pounds from these accounts.

According to the report, for some years, HMRC has been seeking to prosecute a celebrity or other well-known public figure for tax evasion. However, in nearly all cases, potential targets chose to settle with HMRC rather than risk a public shaming.