Cape Town - Schalk Burger's ankle injury is worse than initially feared and he has been ruled out of the Springboks' upcoming Test series against Ireland.

The 86-Test Stormers veteran injured his ankle midway through the second half against the Bulls last weekend, and while he soldiered on to finish that match, he has been ruled out for "four to five weeks".

That means that Burger will miss this weekend's crucial Super Rugby clash against the Cheetahs, but his absence from the Bok set-up will be of more concern to new national coach Allister Coetzee.

There has been doubt over Burger's international future following last year's Rugby World Cup, but Stormers coach Robbie Fleck believes that the 33-year-old still wants to represent his country.

"I think he's always got those Springbok ambitions," Fleck said.

"He's a quality Springbok and he approaches every week like he wants to play for the Springboks. I think the injury is a blow."

Coetzee will announce his squad for the Ireland series on Saturday at 19:00.