Warren Buffett has been buying amid this week's sharp declines in the market, and has not yet seen anything that suggests another downturn is emerging, the legendary investor told Fortune magazine.

In an interview published on Thursday, Buffett also told the magazine he understood why Standard & Poor's lowered its outlook on the credit rating of his conglomerate Berkshire Hathaway , but said he disagreed with the underlying premise - the downgrade of the United States' credit rating.

The 80-year-old Oracle of Omaha is known for his love of a good deal, which is why his company made an unsolicited offer below book value for reinsurance company Transatlantic Holdings last weekend, and why Berkshire sold $2 billion of senior unsecured notes this week at historically low rates.

In that vein, Buffett told Fortune Managing Editor Andy Serwer the market declines have not fazed him.

The lower things go, the more I buy. We are in the business of buying, he said, adding that he had never been better.

Buffett also told the magazine that he was not seeing fresh indications of the economy turning bad again, though things could change if market conditions do not improve.

Up until right now, all of our businesses have been coming back -- even Europe isn't doing that badly -- except for businesses relating to home construction which is on its rear end, Buffett said.

(Reporting by Ben Berkowitz, editing by Dave Zimmerman)