Intel Corp posted stronger-than-expected results but gave only an informal revenue outlook for the current quarter, sending its shares down 5 percent after hours on Tuesday.

The world's top chipmaker reported a net profit in the first quarter ended March 28 of $647 million, or 11 cents a share, down from $1.44 billion, or 25 cents a share, a year earlier.

Analysts had expected a profit of 3 cents a share, according to Reuters Estimates.

Revenue fell 26 percent to $7.1 billion, versus the average analyst estimate of $6.98 billion.

Intel said for internal purposes it is planning for revenue to be flat from the first quarter, compared with analysts' average estimate of $7.0 billion.

Gross margins, a closely watched barometer of its health, were 45.6 percent in the first quarter versus the Wall Street forecast of 43.5 percent. For the second quarter, the company expects margins to be in the mid-40s.

Shares of Santa Clara, California-based Intel rose 3 cents to close at $16.01 on Nasdaq and fell to $15.50 in extended trade.

(Reporting by Gabriel Madway and Clare Baldwin; editing by Richard Chang)