But a top property expert has warned that the boom cannot last, adding that novice investors have left it too late to buy in the North.

"The price increases we've seen are distorted by investor activity and are unsustainable, " said Alan Bridle, a senior research manager at Bank of Ireland in Belfast. "I think the days of the fast buck are nearly over."

He believes prices will slow as London trims the North's public service and increase property-based taxes.

House prices in Northern Ireland grew by 18% in the past year, more than threeand-a-half times faster than the UK average of 5%, according to figures published by Swindon-based Nationwide Building Society last week.

The £129,321 ( 185,000) price of the typical house in Northern Ireland has now overtaken those in Scotland the north of England, meaning it is no longer the cheapest place in the UK to invest.

The average in the south rose to 284,096 in February according to the Permanent TSB house price index.

Brindle said prices are driven by factors unique to Northern Ireland. Because one in three people work in the public service, he said the economy has been much less vulnerable to external shocks.

The property market, traditionally depressed by wage levels that are 20% below the UK average, is also playing catch up, thanks to greater political stability, Bridle said.

Investors have also flooded in, with an estimated one in four coming from the south because of growing demand for private rented accommodation. This is coming from prospective first-time buyers who have been priced out of the market as well as people squeezed off housing lists because of cut backs in funding for public-sector housing.

"Just like in the south, we're seeing strong population growth and a rising immigrant population, " Bridle said.

"Investors, especially from the Republic, see Northern Ireland prices as affordable, especially when compared to prices in Dublin. Some have bought whole streets of houses in parts of south Belfast."

According to official statistics, the total stock of home mortgages stands at £18bn, of which investors account for an estimated £2bn.

"It's estimated that buy-tolet lending is approaching 10% of the mortgage stock in Northern Ireland. It has grown exponentially in the last 24 months. Based on anecdotal evidence, it's estimated that 25% of investors come from the Republic."

They are likely to see a slowdown as the peace dividend leads London to stop pumping money into the North. "I suspect the trigger will be a slowdown in the overall economy caused by downsizing in the public sector and higher local taxes, " said Bridle. "The returns we've seen over the last five years will not be repeated."