An iconic cross-Border project which catches the imagination of the international community would make a dramatic international proclamation that the shooting is over, Dr Edward Walsh, president emeritus at the University of Limerick, told the All-island Infrastructure Investment Conference.

He said there was a strong case for a twin-city region at the centre of the Belfast/Dublin corridor in the Newry-Dundalk region which would act as a "honey pot" for international investment.

Delegates were also told that both jurisdictions had embraced the use of public private partnerships (PPPs) for delivering infrastructure and services.

The Government's NDP had aided the development of a mature PPP market in Ireland, said James Steward, chief executive of Partnerships UK. Much of the criticism of PPPs in the UK has centred on a small number of projects in a £50 billion market covering 700 projects.

"PPPs have improved the way governments procure. A lot of techniques and approaches being used in PPPs are being applied right across the procurement sector and the public sector is getting smarter in the way it procures."

Minister for Finance Brian Cowen defended the use of PPPs in the NDP. "PPPs shouldn't be a replacement model for all public services but there are particular projects where, if you can transfer the risk to the private sector and take up their expertise to make sure the project is delivered on time and on budget, then you really shouldn't argue with the methodology if it helps the wider community and has a public benefit."

Mr Cowen also defended the Government's environmental record and the investment on the State's roads. He said that Ireland would meet its international obligations.