Japanese officials have reportedly accused Jeremy Hunt and Liam Fox of taking a “high-handed” approach towards a post-Brexit free trade deal, and briefly considered cancelling bilateral talks due to take place this week.

The Financial Times cited unnamed officials in Tokyo who reacted with dismay to a letter sent on 8 February in which Hunt, the foreign secretary, and Fox, the international trade secretary, insisted that “time is of the essence” in securing a trade deal with Japan, the world’s third-biggest economy.

Hunt and Fox also called for flexibility on both sides – an approach the paper said had been interpreted as criticism that Japan did not share their desire to quickly conclude a free trade agreement after Britain is scheduled to leave the European Union on 29 March.

The letter, which British officials said had employed standard diplomatic language, had briefly prompted Japanese officials to consider cancelling trade talks in Tokyo this week, the paper reported.

According to the FT, they took exception to a line in which Hunt and Fox said “we are committed to [speed and flexibility] and hope that Japan is too”, interpreting it as an intimation that the Japanese side lacked a sense of urgency.

An official at the Japanese foreign ministry confirmed that the trade talks would go ahead as scheduled, but declined to comment on the contents of the letter or Japan’s response.

“There are many communications over advancing the economic and diplomatic partnership between Japan and Britain,” the official told the Guardian, adding: “But I can’t comment on individual communications.”

The newspaper also reported that Japanese trade officials were growing frustrated with their British counterparts, who had arrived at meetings without specialists capable of taking the talks forward.

Asked about the reports later on Monday, Fox said that most trade with Japan in the past has been done without a free trade deal.

But reports that Hunt and Fox’s letter had irritated Japan are adding to scepticism over assurances made by Brexiters that Britain would ease its way into lucrative free trade deals once it leaves the EU.

To add to Britain’s frustration, Japan has reportedly ruled out simply replicating the terms of a Japan-EU trade agreement that went into effect at the start of this month but which will be unavailable to the UK after Brexit. Instead, it will seek tougher concessions from Britain than it secured from the EU.

Japanese firms, which together employ about 140,000 people in the UK, have made no secret of their alarm at the prospect that Britain will crash out of the EU without a deal.

Earlier this month, Nissan said uncertainty over Brexit was partly behind its decision to abandon plans to build a new model of one of its flagship vehicles at its Sunderland plant.

Reports of Japan’s angry response to the tactics employed by Hunt and Fox emerged days after China abruptly cancelled a crucial trade meeting with the chancellor, Philip Hammond, due to take place in Beijing this week.

Hammond’s visit was called off after the defence secretary, Gavin Williamson, warned that Britain could deploy an aircraft carrier in the Pacific, where Beijing has been involved in a dispute over territorial claims in the South China Sea.