One of Scotland's largest seafood processors has accused state-owned Scottish Water of obstructing new manufacturing jobs by demanding customers pay to upgrade sewage infrastructure.

Pete Ward, chief operating officer of Young's Seafood, which employs 2000 people at six sites across Scotland, expressed his "frustration" that the firm's plan to double the size of its factory at Kirkton, Livingston was being blocked by capacity restraints in the waste-water infrastructure.

"Basically Scottish Water are asking us to pay for their waterworks," he said.

As Scottish Water's Livingston waste water treatment facility is at capacity, the quango is suggesting Young's either pays for extra storage tanks to smooth out the peaks and troughs of its discharge, at a cost of hundreds of thousands of pounds, or that the company finances upgrading of the sewage-processing facilities, at a cost of millions. Ward said the former option would not be a permanent solution for an expanded factory.

Scottish Water has also requested Young's pays for a "feasibility study" of what waste-water arrangements would be needed to service the future population of the industrial estate. Young's, which invested around £11 million in setting up the Livingston plant in 2006, has invested a further £1m each year since then, driving its turnover from £20m to £35m.

For two years, the firm has been exploring ways to increase capacity to facilitate the expansion plans of supermarket Waitrose, the customer for almost all of the seafood products made at Livingston.

"We have a great model whereby as our customer grows, we share in the growth as partner supplier," said Ward. "The nub of the challenge is that we are at consent levels for effluent discharge. We are planning a three to five-year growth plan to double volume for Waitrose. Clearly, increased activity means increased infrastructure. We will need to increase footprint of site but there's no point in doing that without a legal discharge agreement with Scottish Water."

He added: "We have applied for increased [discharge] consent level and that has not been possible. It's crazy to have an industrial site where we and others who want to increase manufacturing can't put in more capacity.

"The Kirkton facility now has 350 jobs, and could grow that number proportionately to any increase in capacity. There aren't many new seafood factories being built in UK, so it was a huge statement of confidence in the area when we came here. We didn't think there would be restrictions on our ability to grow."

Ward, who oversees 10 factories throughout the UK, said the problem was "unique to Livingston", making the company's most modern facility, based in an unemployment blackspot, uncompetitive in UK terms.

"We are a commercial organisation, not a bottomless pit. If it's more expensive to expand in Livingston than elsewhere, it puts the place at a disadvantage.

"On an industrial estate you expect to be able to plug into electrical, gas, or water systems. You expect to have to pay for what you use, but you don't expect to have to pay for the infrastructure itself."

A Scottish Water spokesman said: "Livingston water treatment works already takes effluent from Young's Seafood. This was an agreed amount of effluent to ensure the compliance of the works, agreed after discussions with Young's Seafood prior to their location in Livingston. The works is not able to take more effluent from the factory at the moment.

"Should any infrastructure upgrade be required at our plant as part of the expansion, similar to any other utility, water and waste water would need to be part of the business case by the factory. This would not be funded by Scottish Water customers.

"Scottish Water is happy to work with any organisation or public-sector partner to support the economic growth and development of Scotland and will continue to work to provide the best solution."

A spokesman for CBI Scotland said: "Scottish Water has made great strides over recent years. However, if it were freed from being so reliant on the public purse for its funding, that would provide additional monies which could then be used to tackle water and sewerage capacity constraints which inhibit industrial expansion. The Scottish Government needs to be much more open-minded about ownership and funding."

Young's is owned by Findus and headquartered in Yorkshire.