NEW YORK, US - A portrait of a beaming Michael Jackson by pop art legend Andy Warhol, purchased just weeks ago for less than 300,000 (S$436,050) dollars, could fetch as much as 10 million dollars at auction next month, art connoisseurs said Thursday.

Since Jackson's June 25 death, anything related to the King of Pop has soared in value - as has the 30-inch by 26-inch (76-centimeter by 66-centimeter) Warhol silkscreen and synthetic polymer paint portrait.

The 1984 head-and-shoulders painting shows a 'Thriller'-vintage Jackson: tawny skin and cascading curls, smiling broadly and wearing red and gold-tinged military garb.

A sale of the artwork was to have been held this month, but the Vered gallery, which is selling the work for its unidentified owners, extended the closing date because of unexpectedly strong interest in the portrait.

'We had an overwhelming response,' said Janet Lehr, owner of the East Hampton, New York gallery.

'We stopped the auction. It was supposed to close on July 12th, but there were too many people making inquiries,' said Lehr, who said bidding already is up to 800,000 dollars - three times what the anonymous owner paid for the work in May.