Rugby athlete Katharine Merry has joined a growing list of stars to pull out of this weekend’s Olympic trials in Birmingham after succumbing to a stomach bug.

But the 25-year-old 400m runner is almost definitely assured of a place in the British team as she has already reached the Olympic qualifying standard, and is one of the biggest medal prospects.

The member of the Birchfield Harriers club had hoped to run before her home crowd at the weekend, but decided she was unable to compete.

Last weekend she disappointed fans at Crystal Palace after only coming third. She later revealed she had been suffering from a stomach upset and had been on antibiotics.

Merry only turned to the 400m last year after winning the AAA title that she will no longer be able to defend, and shot to international fame by finishing fifth in the world championships in Seville.

She said:

"I'm very disappointed at having to miss the meeting. But the doctor has told me I must take things easy so I have reluctantly pulled out."

Colin Jackson is also unlikely to compete in the trials in Birmingham’s Alexander Stadium.

He has not competed in the 110 metres hurdles for three weeks after suffering hamstring and thigh injuries.

Malcolm Arnold, Jackson's coach, told The Times:

"It does not look as though he is going to run.

"We will try a hard hurdling session tomorrow but, as things stand, we might have to leave it for another week."

Arnold also refuted claims that the schedule had been changed to give Jackson the chance to run in both the AAA trials and the Weltklasse meeting in Zurich tonight.

He told the UK Athletics website: