One flight had to make an unscheduled landing in Mumbai

Cathay Pacific says its fleet of Airbus planes has been hit by a spate of mysterious toilet blockages.

The problem has been so serious that one flight from Riyadh had to land in Mumbai when the crew discovered none of the plane's 10 toilets were working.

In other cases, the number of passengers boarding flights had to be restricted because of toilet problems.

Airbus engineers are now fitting new toilet pipes to the airline's fleet and carrying out deep cleaning.

Cathay spokeswoman Carolyn Leung said although the exact cause of the blockages was unclear, passengers themselves may be partly to blame.

"You would be amazed what we find in the pipes when we clean the system - not just face towels but medicine bottles, socks, items of clothing and even children's stuffed toys," she said.

The toilets use high-speed vacuum pipes to take waste at up to 110km/h (68mph) into a holding tank, which is then emptied between flights.

Any blockage usually affects all the toilets on one side of an aircraft.