Updated

JOHANNESBURG (Reuters) - Oscar Pistorius has yet to qualify for the 2012 London Olympics despite the double amputee 400 meters runner competing at this year's world championships, the chief executive of South Africa's Olympic Committee has said.

Pistorius ran a personal-best of 45.07 seconds in July, to dip under the 45.25-second qualifying mark for London. The time also allowed the 'Blade Runner' to qualify for the world championships in Daegu, South Korea.

It was assumed that would suffice for a place in South Africa's Olympic team but a tightening of selection criteria by SASCOC means Pistorius will have to run another qualifying time.

"Oscar would have to satisfy the 'A' qualifying criteria as is for able-bodied athletes within the stipulated time period, which I think is within three months of the games," SASCOC chief executive Tubby Reddy told reporters.

SASCOC president Gideon Sam said the tightening of the regulations was to ensure that only genuine contenders will form part of South Africa's Olympic team.

"The criteria works like this: to avoid a situation of a flash in the pan, you make the time but you have to show evidence that again you can make that time," Sam told a news conference.

Sam is targeting 12 medals for South Africa in London and believes that is attainable.

"The dream has certainly not changed at all. We remain very confident in both ourselves and the fact that our athletes will step up to the plate and deliver when they need to," he said.

"It's paramount that we believe in them for them to believe that the whole country is behind them."

(Reporting by Jason Humphries in Durban, editing by Alan Baldwin)