Japan's Komei Oda shot a sizzling six-under-par 66 to take a one-stroke lead after the first round amid tight security at the Casio Open men's golf tournament on Thursday.

Police stepped up security at the Kuroshio Country Club course after a grenade exploded at its clubhouse last week and an anonymous caller claimed to have buried landmines demanding the cancellation of the tournament.

Another grenade went off last Saturday at a local food company owned by the manager of the golf-links.

Oda, who has yet to win a title on the Japan Tour, carded three birdies on both nines without a bogey, one stroke above fellow Japanese Achi Sato and two strokes above Keichi Kuboya and Hiromichi Kubo.

Sato sank six birdies to tie with Oda on the 15th hole, but bogeyed the 17th hole to go back to second place.

Japan's teenage sensation Ryo Ishikawa, 17 who posted his second title on the tour earlier this month, hit a 70 to share 20th place with 13 other golfers.

© 2008 AFP/sid