Oscar Pistorius maintains he is capable of reaching the qualifying standard for August's World Championships in Berlin.

This is despite describing his 400 metres victory at the BT Paralympic World Cup in Manchester Sunday as "shocking".

The 22-year-old, known as Blade Runner due to his prosthetic legs, clocked 50.28 seconds - "the worst time I've run in about three and a half years" - in clinching victory from Manchester's Ian Jones, who recorded a personal best of 51.33secs.

Last year Pistorius successfully appealed against the International Amateur Athletics Federation's decision to exclude him from able-bodied competition before subsequently failing to qualify for the Beijing Olympic Games.

He went on to take three Paralympic titles in the Bird's Nest Stadium in China - in the T44 100m, 200m and 400m - but retains the ambition of competing in both Games in London in 2012.

There appears to be some confusion over the qualification criteria for Pistorius to compete in the IAAF showpiece event in Germany, with the B standard set at 45.95secs - the time Pistorius is targeting - and the A standard 45.55secs, which Athletics South Africa are reported to favour.

However, Pistorius, who rose to prominence with victory in the T44 200m in Athens in 2004 at the age of 17, remains optimistic despite his display at the Manchester Regional Arena.

"I look at that time and think can I make qualifying?" said Pistorius, whose personal best is 46.25secs.

"Let's be honest, it was shocking. It was the worst time I've run in about three and a half years.

"But I know I wasn't running hard and I know I can run better.

"I've got a lot of hard work to do but I've no doubt that I'm going to run a personal best this year.

"I'm sure I'll come close if I don't do it. It is a hard goal but that's what we're in the sport for, to run as hard as we can and to push ourselves."

Pistorius, who was taking part in his first race since Beijing and after suffering serious injuries in a boating accident in February, attributed his performance - in part - to his 100m victory earlier in the afternoon.

Pistorius clocked 11.13secs to pip Paralympic silver medallist Jerome Singleton of the United States on the line, with Jones third.

"The 100 metres time was one of the best times I've run in an easier year (in a season without a major championships)," he added.

"I'm used to be able to focus on a single race - I had about an hour to get ready for the 400."

Jones was thrilled with his performances on his season debut at his home track.

"Two European records, first race of the season, I couldn't be happier, it was really good," said the 19-year-old, who believes he is narrowing the gap to Pistorius.

"I've got to keep plucking along - I'm still, in my mum's eyes anyway, a baby and he's got a couple of years on me.

"I ran well today. I've got to keep progressing and we'll see how it goes."

Wheelchair racer David Weir, who secured both of Britain's athletics golds in Beijing, took silver in the men's T54 800m and 1500m gold after leading from the front.

The 29-year-old from Wallington, Surrey, only returned to training in January after taking some time out following his Beijing exploits and was pleased with his first race back on the track.

"I didn't want to see my racing chair for a little while (after Beijing)," said Weir.

"I've been racing for 20 years and I thought I needed the time out to see friends and family."

Weir's 2009 targets include the Grand Prix at Crystal Palace and the New York marathon, as well as the Great North Run.

Also victorious at the fifth edition of the BT Paralympic World Cup were Libby Clegg, who is partially sighted, in the women's T12 100m and Ben Rushgrove, who has cerebral palsy, in the men's T36 100m.

Michael Churm, Katrina Hart and Robin Womack took silver medals in the men's T37 100m, the women's T37 100m and the F54-57 shot put, respectively.

Blackpool wheelchair racer Shelly Woods and Sophie Hancock each won two bronze medals - in the T54 800m and 1500m, and in the F40 discus and F40 shot put, respectively.