By Martyn Herman

LONDON (Reuters) - Defending champion Serena Williams has been seeded seventh for next week's Wimbledon championships but sister Venus is lurking down at 23rd after the All England Club's seedings committee met on Wednesday.

The sisters were originally seeded eighth and 24th but their positions were revised following the withdrawal of second seed Kim Clijsters.

The U.S. and Australian Open champion pulled out of the tournament on Wednesday after injuring her foot at the Den Bosch Open.

The 29-year-old American required surgery on her foot after slicing it open on broken glass in a Munich restaurant last July and then needed emergency treatment in February for potentially life threatening blood clots on her lungs.

She returned to action this week at Eastbourne after taking a wildcard.

The rest of the seedings follow the WTA rankings with Denmark's world number one Caroline Wozniacki topping the draw.

The men's seedings, based mainly on the ATP rankings on June 13 but which can be tweaked to reflect grasscourt form, have a top four of defending champion Rafa Nadal, Novak Djokovic, six-times champion Roger Federer and Andy Murray.

American Andy Roddick, three times a runner-up, has earned the eighth seeding spot despite a current ranking of 10 which means he will avoid the "big four" until the quarter-finals.

Frenchman Jo-Wilfried Tsonga has also been shunted up to 12th from a ranking of 19 after his run to the Queen's Club final where he lost to Murray.

(Additional reporting by Toby Davis; Editing by Mark Meadows)