The Tánaiste, Ms Mary Harney, said she has sought and been given assurances by the Taoiseach, Mr Bertie Ahern and others in Government there is no "truth whatever in the [latest] allegations".
The allegations come from newspaper reports that a serving Cabinet member received an £80,000 payment.
"As far as I’m concerned I’m not going to compromise my strongly-held beliefs in the interest of staying in Government," she added.
She was speaking as the Progressive Democrats launched their Yes to Nice campaign in Dublin today.
Ms Harney said a Yes vote would create new jobs while protecting existing jobs.
She said: "Vote yes to give other countries the chance we had and to secure your right to decide on neutrality."
She criticised the No campaign and accused Mr Joe Higgins of the Socialist Party of making "wild accusations" when he outlined the possibility of wholesale privatisation of services including water, electricity and the post office if the Treaty was ratified.
She also warned, "the international investment community would interpret a No to Nice as Ireland saying no to Europe. We might not see the impact immediately but we would see it over time."
