NEW YORK - Carnival Corp, the world's largest cruise ship operator, cut its second-quarter and full-year earnings outlook, citing higher fuel costs and a falling U.S. dollar.

In a filing with the Securities and Exchange Commission on Thursday, Carnival lowered its second-quarter earnings outlook by a penny per share and reduced its full-year forecast by 6 cents a share.

Moody's revised its rating on the Miami-based company to negative from stable on Friday.

Carnival said last month it expected to earn between 30 cents and 32 cents per share in the second quarter and $2.10 to $2.30 for the full year.

Higher fuel costs and a faltering dollar were the main reasons for the lowered outlook, Carnival said. Last year, the stunning drop in fuel costs and a stronger dollar helped offset the contraction in consumer spending prompted by the economic downturn.

The company now expects second-quarter and 2009 fuel costs to be around 3 percent higher than it previously outlined, and sees the U.S. dollar stumbling against the euro and the sterling.

Moody's cited falling travel demand as a reason for the downgrade, saying it would lead to lower net revenue and deteriorating debt protection measures.

Carnival stock rose 45 cents to $24.64 on Friday on the New York Stock Exchange. (Reporting by Deepa Seetharaman; editing by Jeffrey Benkoe)