Dublin - Irish Prime Minister Brian Cowen on Wednesday ruled out a third referendum on the Lisbon Treaty if Irish voters rejected it in the upcoming second referendum.

"There won't be a Lisbon III, I think that's for sure," Cowen said, when hypothesizing over a possible defeat of the treaty in the referendum to be held on Friday.

The Irish leader however warned that a defeat would lead the European Union into crisis.

"I think what's clear is that we face into a period of extraordinary uncertainty in Europe, for Europe, and what direction it would then take," Cowen said.

"We could well see the development of a two-speed Europe," he added, calling on voters to back the treaty that he said would help Ireland recover from the worldwide financial crisis that has led to 12-per-cent unemployment and a property crash in the country.

He said the electorate's concerns over the treaty had been addressed by legal guarantees that the reforms would not affect Irish neutrality, taxes, family law and rights to a Commissioner. (dpa)