Rising prices for steel and other materials are reported to have driven up the cost of wind turbines by a fifth in two years.
These big rises risk increasing the cost of electricity from new projects.
The Times says that offshore wind developers are now calling on the UK Government to raise the budget of this month’s auction to support fresh developments.
Trade association RenewableUK says a few per cent on the price of electricity from new projects would mean it was still cheaper than gas-fired generation.
The UK has a target of 50 gigawatts (GW) of offshore wind operating by 2030 - up from about 10GW today.
The Government encourages investment by guaranteeing a fixed price for the electricity.
A reverse auction decides how many projects get the go-ahead and at what price. The most recent, in 2019, saw the price fall to a record low of £39.65 per megawatt-hour (MWh).
Dan McGrail, head of RenewableUK, said the £200million annual budget in the next auction was expected to procure about 6.4GW of offshore wind at about £38 per MWh.
However, the cost of steel used to make turbine towers and foundations has surged. The contract price needs to increase again by "a couple of pounds" or else it may be too low to "support supply-chain development in the UK".
And if developers seek higher prices but the budget is unchanged, this could result in less capacity being built.
RenewableUK said that increasing the budget by £68million would both enable developers to recoup higher costs and support the construction of 2GW more than originally expected.
A Government spokesman said the next auction was "expected to secure more cheap renewable energy capacity than the previous three rounds put together".
Plans which could see an average spend of £1.5billion in Scotland on each of 17 new offshore wind projects were published at the end of last month by Crown Estate Scotland.
This represents a massive investment of more than £25billion from successful applicants in the recent ScotWind leasing round.
The 17 projects have a combined potential capacity to generate up to 25GW of energy.
For perspective, the current capacity of offshore wind in Scotland is almost 2GW - and another 8.4GW is in construction or advanced development.