The centrepiece of the Glasgow Science Centre will be closed for at least two months after engineers discovered the £10m Glasgow Tower has sunk by around 15mm.

The tower, which opened in October 2001 as part of a £75m Millennium project, is a 400ft structure that turns through 360 degrees with up to 15 people in an observational pod. Since its opening it has attracted nearly 40,000 visitors.

As part of a routine inspection, engineers found that two bearings at the base of the Tower need replacing, and an investigation is now underway to determine the effects of water and oil seepage.

'Obviously it is an inconvenience and we regret the loss of the facilities, but we are working on restoring normal service as soon as possible,' said a spokesman for the Glasgow Science Centre. 'The tower is designed for the bearing to require replacement periodically, so this is a situation we expected, but it has arisen more quickly than we would have liked. However, it is a temporary problem, and we will get over it.'