British Airways will operate 90 per cent of its timetable at London Heathrow airport's new Terminal 5 by the end of this week, according to a spokesperson from the airline.

Currently the airline is operating 87 per cent of its schedule at the terminal, with around 50 flights cancelled. By Friday, only 34 flights, or less than 10 per cent, will be cancelled, said British Airways spokesman Anthony Cane.

Cancellations caused by snags in the £4.3 billion terminal's computerized baggage system total more than 350 since the facility opened March 27.

The airline has had to bring in courier firms and 400 volunteers from its own workforce to help clear a backlog of about 20,000 bags.

"We are working around the clock to try to deliver the delayed bags as soon as we can and that 20,000 figure is changing all the time," said Cane.

The airline had been relying on Terminal 5 to ease journeys and retain passengers put off by Heathrow's overcrowding.

British Airways fell 1.75 pence, or 0.7 per cent, to 247.5 pence. The stock has declined 20 percent this year, reducing the London-based company's market value to £2.85 billion.