UUP leader Sir Reg Empey said that whatever republicans' short-term or long-term political agenda, they were selfishly not taking into consideration the harm they are doing to the local economy.

"During May we had a US Investment Conference and much was made of the fact that we had political institutions and a country that was now stable; not least by Martin McGuinness, who was selling us as such," he said.

"It will now appear to those would-be investors that we brought them here under false pretences. Within days of Sinn Fein telling them all was well, they were threatening (in June) to close down government and then warning they would not agree the nomination of the Deputy First Minister."

"People are entitled to ask: 'how is that compatible with McGuinness running round New York earlier this year, ringing the bell at the New York Stock Exchange and saying all is well?'. If US business people are serious about investing here, in what is a very difficult climate, what sort of message is being sent to them now?"