World No 1 chess player Garry Kasparov's latest attempt to conquer a computer programme ended in a tie on Tuesday when he drew the fourth and final game of his match against 'X3D Fritz', which had voice-recognition and virtual reality features.

Kasparov, 40, said after the weeklong match at the New York Athletic Club that computer programmes were stronger now than the IBM supercomputer Deep Blue he took on in 1996 and 1997, the benchmark for man vs machine contests.

"Machines are getting better, but we humans are also learning," said Kasparov, considered by chess experts to be the best player in the history of the ancient game. "Today, I know much more about computers than six years ago."

The grandmaster and the computer's programmers agreed to a draw in Tuesday's fourth game after about 90 minutes and just 27 moves, the shortest game of the series that began with a November 11 draw. X3D Fritz won the second game last Thursday when Kasparov blundered. The grandmaster won comfortably on Sunday.

In chess, one point is awarded for a win and a half point for a draw. The match ended in a 2-2 tie.

In February in New York, Kasparov tied a six game match 3-3 with Israeli-built world chess computer champion Deep Junior. A version of German-built Fritz tied an eight-game match 4-4 last year with world champion Vladimir Kramnik of Russia.

Azerbaijan-born Kasparov lost his world title to Kramnik in 2000 but is still rated No 1 in International Chess Federation rankings. X3D Fritz is a combination of Fritz software that is sold commercially and the New York-based X3D Technologies company's virtual reality software.

Kasparov played without physically moving pieces on a board. He sat in front of a monitor wearing black 3-D glasses that made the image of the board appear to float in front of him. In another departure from tournament chess and other computer matches, Kasparov announced his moves into a voice-recognition programme.

Chess experts said Kasparov handled the technology well.

"One of the questions before the match was whether the 3-D environment would be very difficult for Garry and he has shown that he can tie a match in a 3-D situation," said David Levy of the International Computer Games Association, which sanctioned the match broadcast on several chess web sites and the ESPN2 US cable TV sports channel.