The government has been accused of “anti-competitive” and “distortionary” behaviour by Eurotunnel, after awarding a series of no-deal Brexit contracts to shipping companies including a startup that has yet to run ferry services.

Jacques Gounon, the chief executive of Getlink, the cross-channel rail operator’s parent company, told the UK transport secretary, Chris Grayling, the contracts may have been illegally awarded.

“It is with serious concern that we have read in this weekend’s press details of agreements between HMG [Her Majesty’s government] and certain ferry operators up to £107m to provide additional capacity to be sold into the market even if a deal is reached,” he wrote.

“I must bring to your attention the distortionary and anti-competitive effects of such an action, which would be a unilateral breach not only of the concession agreement with Eurotunnel, but more widely of existing competition and state aid law.”

Gounon was speaking after the controversy over a £14m contract awarded to Seaborne Freight, a startup company, to revive a ferry service from Ramsgate in Kent to Ostend in Belgium.

The company did not have any ships at the time of the award and is in the process of chartering them.

He pointed out Eurotunnel offered the quickest link to France and the company had already been working on contingency options the government was aware of, including additional freight trains and a terminal for unaccompanied trailers, but added that this needed government support.

Gounon said the company was ready and waiting for the government to act and “remains prepared to deliver additional capacity under equivalent contracts to those you have signed with ferry operators”.

Eurotunnel was one of the first companies to warn the government of the potential risk Brexit posed to transport in Kent. It is deeply frustrated by what Eurotunnel described as the government’s lack of engagement.

A dredger at Ramsgate harbour. Photograph: Sean Smith/Guardian

Grayling announced on Christmas Eve that the government had awarded £103m to three ferry companies to provide additional cargo capacity in the event that the Dover-Calais route becomes congested in a no-deal Brexit scenario.

The largest contracts went to Brittany Ferries and the Danish cargo company DFDS, with the third going to Seaborne Freight.

Grayling defended his department’s accelerated tender process and said he made no apologies for supporting a British startup.

But Grayling was also criticised by the chief of Calais port, who said he was “very angry” over the deal between the government and Seaborne Freight.

“I’m very shocked, I consider it disrespectful for Calais and Dover,” said Jean-Marc Puissesseau.

Portsmouth port has expressed its frustration with the government over plans to use nearby land for lorries, and said part of the M3 may be closed to provide space for these vehicles in the worst-case scenario.

Seaborne Freight’s chief executive, a former Royal Navy submarine officer, has defended the government’s decision, saying the company is run by a collection of experienced “old dogs” who will charter, rather than own, cargo ships.

A councillor in Ramsgate warned the port will not be ready for services in April. It has not been used as a ferry terminal for some years and only last Thursday did excavation of the seabed begin, so ferries and large cargo ships can start operating out of the harbour again.