WASHINGTON (Reuters) - Mitt Romney said on Sunday he will release tax returns for the last two years on Tuesday after he came under attack from rivals for delaying his financial disclosures.

"I will release my tax returns for 2010, which is the last returns which were completed, on Tuesday of this week," Romney said on Fox News Sunday. "And I will also release at the same time an estimate for 2011 tax returns."

(Reporting By Mary Milliken; Editing by Philip Barbara)