CONTRACTOR MOWLEM is demanding an extra £2.75M from Portsmouth City Council to complete the £16.5M Spinnaker Tower in the city.
Mowlem's claim relates to the need to replace the planned rack and pinion lift in the 165m high tourist attraction with a more expensive conventional lift.
'This is one of a number of design and technical issues that has evolved in recent times, ' said Portsmouth City Council project manager Mike Broomfield.
'It's an asymmetric structure where the load is eccentric to the main shaft and there are not many of those. The ground level deck has also proved very complex as there is a 165m structure to go on top of it. It has taken longer than envisaged.'
The original completion date of summer 2003 is now expected to go back by several months.
Spinnaker Tower comprises curved steelwork tied back to a concrete A-frame. It is part funded by a £5M lottery grant (NCE 8 November).
Mowlem is understood to be claiming the extra cash on the basis that price of the design and build project had not been fixed as a formal contract has not been signed.
Work started on the basis of a letter of intent from Portsmouth City Council in February 2001 which Broomfield said 'is not unusual in our business and without which many projects would be delayed'.
A Mowlem spokeswoman said: 'A number of technical and contractual matters have arisen on the Spinnaker Tower project and we are currently in discussion with Portsmouth City Council to resolve them. Work is ongoing on site and we hope that all issues will be resolved shortly.'