US presidential challenger Mitt Romney said that he won't release his tax records from before 2010 because his opponents would "pick through, distort and lie about'' them.
The Republican hopeful is under pressure from Democratic incumbent Barack Obama's campaign - and from many on his own side - to quell speculation about his wealth by releasing his financial records to public scrutiny.
But, in an interview with the conservative website National Review Online, Romney said he had already released his most recent records from 2010 and would not be going further back to quiet his critics.
"In the political environment that exists today, the opposition research of the Obama campaign is looking for anything they can use to distract from the failure of the president to reignite our economy,'' Romney said.
"And I'm simply not enthusiastic about giving them hundreds or thousands of more pages to pick through, distort and lie about.''
Romney is a former governor of Massachusetts and a multimillionaire businessman with a huge personal fortune dating back to his time as the head of a Bain Capital, a private equity firm he founded.
Ahead of the November poll, Romney is challenging Obama on his economic record, arguing that, as a successful private sector manager and investor, he is better-placed than the Democrat to turn around the still sluggish US economy.
The president has countered by painting Romney as a heartless asset-stripper whose firm Bain often bought US firms simply to break them up, sack workers and ship American jobs abroad.
They have also questioned why he has offshore bank accounts and refuses to reveal his tax returns, saying they would show that he pays a relatively low effective rate on his income thanks to canny accountancy.
Asked why he had not liquidated his offshore investments before running for office, Romney said there was nothing shady about the arrangement.
"Well, first of all, all of my investments are managed in a blind trust. By virtue of that, the decisions made by the trustee are the decisions that determine where the investments are,'' he told the National Review.
"Secondly, the so-called offshore account in the Cayman Islands, for instance, is an account established by a US firm to allow foreign investors to invest in US enterprises and not be subject to taxes outside their own jurisdiction.
"So in many instances, the investments in something of that nature are brought back into the United States. The world of finance is not as simple as some would have you believe,'' he argued.
"Sometimes a foreign entity is formed to allow foreign investors to invest in the United States, which may well be the case with the entities that Democrats are describing as foreign accounts.''