The Irish unit of Intel, the world's No. 1 chipmaker, on Thursday launched a campaign in favour of a Yes vote in the October referendum on the European Union's Lisbon reform treaty.

Groups such as the Irish Business and Employers Confederation and the American Chamber of Commerce have already pledged their support for the accord, which is designed to streamline EU decision-making.

The decision by Intel, one of Ireland's biggest employers with 4,500 staff, to spend what it said would be a few hundreds of thousands of euros of its own funds on a campaign underlines the importance of the vote to businesses.

I believe (in) business standing up and ... saying that it matters for business for growth ... playing a full role at the heart of Europe, General Manager Jim O'Hara told a news conference.

Irish voters rejected the treaty in June 2008 but the government has agreed to organise a second referendum after winning concessions from European partners on issues of key importance for Ireland such as abortion and military neutrality.

Opinion polls show a majority of voters now support the treaty as increasing numbers accept Ireland could not have coped with twin fiscal and banking crises and the worst recession on record without support from the European Central Bank and Brussels.

If for the third time in less than ten years we reject an EU treaty, we must realise this will create uncertainty in the minds of investors, O'Hara said, referring to Ireland's two votes on the Nice treaty, an earlier EU accord which also failed to pass the first time around.

(Reporting by Andras Gergely; editing by John Stonestreet)