Northern Ireland's Finance Minister Sammy Wilson has accused Ireland of "stealing" tax revenue from the UK.
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.
– Northern Ireland's Finance Minister Sammy Wilson talking to 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.
Irish junior finance minister Brian Hayes rejected claims Ireland was a tax haven.
– Ireland's junior finance minister Brian Hayes
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.
Anti-poverty campaigners are urging David Cameron to build on his agreement with Britain's network of Crown dependencies and overseas territories to forge a global deal on tackling tax evasion.
Ahead of the G8 summit, the Prime Minister also announced plans to establish a register of beneficial ownership in the UK - requiring opaque "shell" companies to declare who were the ultimate beneficiaries of their operations.
Campaigners, who welcomed the announcements, said they were only a first step in ensuring developing nations are able to collect the billions they are entitled to in tax revenues.
Melanie Ward, of the Enough Food for Everyone IF campaign, said although Mr Cameron had "cleared a big obstacle" when it comes to clamping down on tax evasion, the "acid test" would be whether he delivers a similar deal with the G8 countries.
Michael Elliott of the ONE campaign said: "We need to see more progress on these issues over the coming days. By taking these steps, the G8 can make sure that it not only puts its own house in order, but does so in ways that work for people beyond the G8 too".
Speaking after meeting with the network of overseas territories and Crown dependencies, David Cameron said: "if companies don't properly pay their taxes or individuals don't properly pay their taxes we all suffer as a result, so it is important that we get our house in order."
David Cameron has secured an agreement from Britain's network of overseas territories and Crown dependencies to sign up to a new clampdown on tax evasion.
At talks at Downing Street ahead of next week's G8 summit at Lough Erne, the leaders all agreed to a series of actions aimed at promoting transparency and exchange of information between tax jurisdictions.
The Prime Minister hailed the agreement as a "very positive step forward" which would strengthen his hand in talks with the other G8 leaders in which he has made improving international tax compliance a key issue.
Treasury Chief Secretary Danny Alexander said ministers hoped that other countries would be prepared to create their own registers of beneficial ownership.
He told the BBC Radio 4 Today programme: "It would be preferable for every country in the world to have such a register and then for that information to be shareable and shared openly between tax jurisdictions.
"There are a lot of changes that we are making to our own tax system to ensure that we can collect the tax that people owe.
"But we are also trying to make sure that, for the good of the UK but also for the good of the developing world too, that this information is shared and open so that every country in the world can get the tax that they are due."
Labour leader Ed Miliband has welcomed the move to establish a set of global standards to tackle tax evasion.
However, Mr Miliband also warned David Cameron that he must be prepared, if necessary, to get tough with any countries which refuse to comply.
Writing in The Independent, the Labour leader said Britain "needs to use all its considerable legal power and authority to ensure all the UK overseas territories and Crown dependencies which act as tax havens sign up".
The Prime Minister has promised to "sweep away" tax secrecy in Britain as he seeks to persuade the leaders of the G8 to agree to establish a set of global standards to tackle tax evasion.
David Cameron said he will a introduce a new central register requiring the true owners of "shadowy" shell companies to be declared to the tax authorities.
In an interview with The Guardian, Mr Cameron said he was determined to put an end to the notion of "secretive companies in secretive locations", which cost the UK billions of pounds in lost tax revenues.
He told the newspaper: "We need to know more about who owns which company - beneficial ownership - because that is how a lot of people and a lot of companies avoid tax, using secretive companies in secretive locations.
"The way to sweep away the secrecy and get to the bottom of tax avoidance and tax evasion and cracking down on corruption is to have a register of beneficial ownerships so the tax authorities can see who owns beneficially every company".
David Cameron will tell leaders from Britain's network of overseas territories and Crown dependencies that they must do more to clamp down on tax evasion and aggressive tax avoidance.
The Prime Minister has summoned representatives for talks in Downing Street today ahead of next week's G8 Summit in Northern Ireland, where he has made international tax compliance one of the main issues on the agenda.
The move reflects an acknowledgment by Mr Cameron that the UK needs to "get its own house in order" if he is to persuade the G8 leaders to sign up to the development of a set of global standards on the exchange of information between tax authorities.
Many of the islands and outposts are regarded as tax havens - a description they bitterly dispute.
Mr Cameron will welcome commitments that have already been made to join a pilot project being launched later this year to trial information exchange procedures.
But he will press the leaders to go further and sign up to the Organisation for Economic Co-operation and Development's convention on mutual assistance in tax matters.