Northern Ireland's Finance Minister Sammy Wilson has accused the Irish government of "stealing" UK tax revenue.
The Democratic Unionist said he was concerned that companies were using the Republic of Ireland to pay tax which he alleged should be paid in the UK but the Irish government has defended its tax laws.
Mr Wilson told the BBC: "My view is that the British Government does have some leverage on the Irish government there, because they have a £7.5 billion loan, that is a lot of leverage. They should be saying to the government in the Republic, you cannot steal tax revenue from us in this way and that is in fact what has been happening."
David Cameron has put tax and transparency at the heart of next week's G8 agenda and wants the meeting to include country-by-country reporting of where companies pay their tax.
Irish junior finance minister Brian Hayes rejected claims Ireland was a tax haven.
He said: "It is wrong and it is put out there by countries I suspect who are looking to the success we are making of this country in terms of inward investment. The fact of the matter is this: it is not Irish tax law that is at stake here, it is other jurisdictions with their tax law."
Labour MP Margaret Hodge has claimed internet giant Google operated contrived tax arrangements to avoid UK corporation tax. Google's claims that its Irish operation, where lower rates apply, is responsible for hundreds of millions of pounds in advertising sales in the United Kingdom are "deeply unconvincing", an influential House of Commons committee found.
Following complaints about the tax paid by multinationals operating in Britain, Google, which has enjoyed UK revenues of £12 billion since 2006, claimed its British-based staff were not responsible for selling. The House of Commons public accounts committee this month said the company's defence has been undermined by whistleblowers and reporters.
Separately, Ireland has rejected claims by two US senators that the country was a tax haven and had handed technology giant Apple a special deal. Ireland's ambassador to the US, Michael Collins, has written to senators Carl Levin and John McCain arguing that Ireland's tax system is transparent.
However, the lawmakers said records obtained by their committee showed Apple, which has about 4,000 employees in Ireland with most based in Cork, paid a nominal rate far below Ireland's corporate tax rate of 12.5%.