Michael Lodge, a British lawyer and the head of the UN-affiliated body responsible for governing mining in the high seas, has been criticised by diplomats who claim he has been pushing them to accelerate the start of deep-sea mining.

A German diplomat said Lodge – the secretary-general of the International Seabed Authority (ISA) – has a duty of neutrality and has overstepped his role in resisting measures put forward by some council members that could slow down approval of the first mining proposals, according to the New York Times.

Furthermore, in a tweet referencing the story, Gina Guillén Grillo, Costa Rica’s representative to the seabed authority, said yesterday: “Member states should drive the International Seabed Authority. Decisions must come from them & must not be pushed by those who have only administrative duties. Mining the seabed cannot be rushed [because] of the economic interests of a few.”

The criticism of Lodge comes at a crucial juncture as the body is expected to receive an application for commercial seabed mining later this year. The authority, which is meeting in Jamaica this week, is still writing regulations that would govern the process.

Germany and Costa Rica are among the increasing number of countries – including France, Spain, Chile, New Zealand and several Pacific nations – that have recently said they do not believe there is enough available data to evaluate the impact of mining on marine life. They have called for a “precautionary pause” or a ban on mining in the high seas.

Lodge has previously suggested environmental impacts from deep sea mining are “predictable and manageable”.

The German government sent a letter to Lodge last week expressing its concerns. In the letter, Franziska Brantner, Germany’s minister for economic affairs and climate action, said: “It is not the task of the secretariat to interfere in the decision making. In the past, you have actively taken a stand against positions and decision-making proposals from individual delegations.”

Brantner added that the German government “is seriously concerned about this approach”.

In a reply to Brantner the next day, Lodge described those complaints as “a bold and unsubstantiated allegation, without facts or evidence”.

Lodge said his job was to make sure the authority respects the “legal framework” of the law of the sea. He said his opening remarks on 8 March “did not refer to any specific proposal by any delegation” but were fully consistent with “the competencies recognised to me” and that it was false to suggest he had in the past taken positions opposing proposals from delegates. “This is untrue and I reject such a baseless allegation,” he said. He asked the German delegation to respect him and his staff and “not seek to influence them in the discharge of their responsibilities”.

Lodge made a statement to the New York Times saying that he places “high importance on the preservation and protection of the marine environment”, and that he is working “to ensure that decision making processes around economic activity in the deep seabed is based on best available scientific knowledge”.

The row is a measure of growing tensions over who controls the agency, amid pressure from some UN nations to slow down ocean mining, while others want it to go ahead.

Duncan Currie, an international legal adviser to the Deep Sea Conservation Coalition and an official observer at the 8 March meeting, told the Guardian: “This is not just a row between diplomats. It is very significant. The executive organ is the council. It is not for the administrative body to be telling the council what decisions they should be making.”

The debate has heightened in recent months because the The Metals Company, a Canadian mining startup, has said it intends to request approval this year to start mining as soon as 2024.

The small Pacific island country of Nauru is one of three states sponsoring The Metals Company, along with the Kingdom of Tonga and the Republic of Kiribati. In 2021, Nauru triggered a two-year rule that obliges the ISA to finalise and adopt regulations for commercial mining by July 2023.

According to a memo sent by the Republic of Nauru, if the ISA has not finalised regulations within the time frame, and a mining application has been submitted, then the authority should “nonetheless consider and provisionally approve” it, allowing for extraction to go ahead.

However, some authority members believe the agency is under no obligation to approve an application from The Metals Company and Nauru until the regulations are complete.

Diplomats were called to a virtual meeting on 8 March to discuss what to do if a mining application was indeed sent this year. As reported by the New York Times, some delegates suggested revisions to the permitting process that would strengthen the council’s ability to block the start of mining.

However, according to a copy of his prepared remarks Lodge warned delegates not to change established procedures. “It would be dangerous to disturb this balance,” he said. “We should let the system work as it is intended to do.”

Lodge said he did not intend to challenge any delegation’s proposals. But his remarks were interpreted that way by Germany, Costa Rica and France, the New York Times said.

A spokesperson for the ISA told the Guardian: “The role of the secretariat is not to pass judgment on the position of member states, but to facilitate negotiations and ensure that discussions are informed by the best available science and in accordance with the United Nations Convention on the Law of the Sea and the 1994 agreement. The secretariat carries out this mission carefully, deliberately and to the best of its abilities.”

The spokesperson added: “The regulations will only be approved should ISA’s members reach a consensus on its content. In the meantime, only exploration activities will be permitted.