Beth Tweddle has been forced to withdraw from two disciplines at the Beijing Olympics, it was confirmed today.

The 23-year-old British gymnast has been struggling with a rib injury and will not compete in the vault or the beam events but insists she is fully fit for the asymmetric bars and floor disciplines.

"This was going to be my last four-piece competition but I've got to do what's best for the team," said Tweddle, who arrived in Beijing yesterday after staying on at the Team GB holding camp in Macau for additional physiotherapy.

"I'm fully fit for the bars and the floor, which are my two strongest events. My main aim is to help the team qualify for the team final.

"We finished sixth at the world championships last year, so we're an outside chance for getting a medal."

Injuries have hampered Tweddle's career. After winning Britain's first ever gymnastics world title, on the asymmetric bars in 2006, she was forced to miss the Commonwealth Games in Melbourne with an ankle injury. Tweddle was denied the chance to defend her British all-around title earlier this year by another ankle injury and had only just recovered from it when she developed a rib problem.

Tweddle, a sports science graduate, is heading into her last Olympics. She plans to retire after next year's world championships in London to embark on a second career in physiotherapy. After claiming world, European and Commonwealth titles, she has said a medal of any colour in Beijing would be the "icing on the cake".