Management have written to all 20 elected members outlining their concerns about the Port development, which has already attracted marquee tenants B&Q, Costa Coffee and Marston’s.

Officials working on behalf of the centre say they want to make sure councillors are ‘fully briefed’ about the impact further development at the retail park will have on businesses elsewhere.

The letter says the Port park could wipe out a fifth of the Oak Mall’s tenants.

In it, Iain Minto, on behalf of M&M Property Asset Management LLP, said: “I represent the owner of the Oak Mall Shopping Centre in Greenock and feel obliged to write to you, as an elected representative within Inverclyde, to make sure that you are fully briefed about the consequences of Inverclyde Council permitting the development of 190,000 square feet of retail space at Port Glasgow which is to be considered on 4 March.

“We bought Oak Mall on 20 March 2014 for £35 million. On 2 February 2015 we committed up to £4 million on floor replacement and flood mitigation works. In addition we will be submitting a PAN (Proposal of Application Notice for future major development) over the next few days which will provide details of a proposed space multi-storey car park of around 400 spaces which will cost up to £3m.

“We have a full project team appointed who are also developing ideas for further improvements around the Oak Mall centre.

“We are continuing to look at ways to create opportunities for Oak Mall which will protect the interests of the 600 members of staff already employed there and improve the offer to the 97,500 visitors we attract on a weekly basis.

“The planning application lodged by Ediston Retail Estate, if granted, will provide up to 190,000 square feet of retail and leisure just a few minutes away from Greenock, the strategic town centre as defined by the Local Development Plan.

“In light of this we have grave concerns about the sustainability of retail in Oak Mall and the town as a whole.” Mr Minto added: “We believe that if this development goes ahead we will lose 20 per cent of our existing tenants by floor area to the retail park, the retail provision in Oak Mall will shrink by a third and the town itself will lose all the remaining regional and national retailers.

“In other words there will not be more income and jobs created, purely a displacement of economic activity which will have a disastrous effect on Greenock and the remainder of Inverclyde.” He added: “You should be under no illusion that we are in complete opposition to the proposal.

“As a commercial investor we have every intention in improving and sustaining the Oak Mall and Greenock town centre.

“However, should the scheme be granted permission we will be obliged to our funders to carry out a comprehensive re-assessment of our investment in Oak Mall which may lead to a reduction in our investment plans or even their suspension pending a disposal.

“We sincerely hope that it will not come to this.

“We have spent a considerable amount of time and effort in looking at Oak Mall and do not believe that any other investor is likely to have the same commitment.”