Britain’s new member of the European Commission, Sir Julian King, will have a narrowly focused role dealing with organised crime and counter-terrorism issues, it was announced on Tuesday, as Brussels moved to settle the delicate issue of how to allocate responsibilities to a commissioner from a country on course to exit the EU.

The European Commission said in a statement that Sir Julian would be handed the title of “Commissioner for the Security Union” but at the same time made clear that the role would be tightly defined and largely focused on operational measures rather than policymaking.

In a “mission letter” published on Tuesday, Jean-Claude Juncker, the commission’s president, said that no responsibilities would be reallocated to Sir Julian from existing commissioners, meaning in practice that much of the policymaking power over security issues would remain with Dimitris Avramopoulos, the EU home affairs chief.

Mr Juncker also said in the letter that it would continue to be Mr Avramopoulos, and not Sir Julian, who will in general represent the commission in the European Parliament and at meetings of national ministers. According to the mission letter, Sir Julian should focus on “concrete operational measures” and “support” Mr Avramopoulos in his work.

Elmar Brok, the chairman of the EU parliament’s foreign affairs committee, told the Financial Times that Sir Julian would be “a type of junior commissioner” when it came to his portfolio. He noted, however, that Sir Julian would have a full vote in the EU commission’s ruling college, and that it was this voice in decision-making that was probably the most important thing for the UK.

A spokeswoman for the commission said that Sir Julian’s job was a “cross-cutting portfolio” that would require him and his colleagues to work in a “team spirit”.

Sir Julian, a former UK ambassador to France, was nominated by David Cameron in July as a replacement for Jonathan Hill, who resigned in the immediate aftermath of the Brexit vote. Lord Hill had held the high-profile position of financial services commissioner, a role long-coveted by the UK, but said that it would be “wrong” and politically unsustainable for him to continue. His responsibilities were immediately reallocated by Mr Juncker.

The operational nature of Sir Julian’s role sidesteps the political dilemmas and likely resistance in the European Parliament that would have arisen had he been given a major political-making role. Mr Brok, a German MEP and a leading member of Angela Merkel’s CDU party, said that it was unthinkable, for instance, that the UK commissioner could have be given responsibility for an economic policy portfolio, given that Britain is heading for the EU exit door.

Mr Brok said that a big task facing Sir Julian would be to try to encourage national security agencies to work more closely together, after gaps in intelligence sharing were exposed by recent terror attacks. This is a “very important” task and an area where the EU has been failing, he said.

Mr Juncker’s mission letter specifically mentions the need to upgrade a European Counter Terrorism Centre being developed within Europol, the EU’s law enforcement agency.

A Downing Street said the government welcomed the decision.

“Security is a vital issue for all member states and co-operation across the EU can help to better protect us all from the range of threats we face,” it said. “The UK will continue to fulfil our rights and obligations as a member state until we leave the EU … so it is right that we should continue to have a Commissioner role.”

The new British commissioner will not be given his own department but will instead will be allocated a task force of officials from across various parts of the institution. The set-up is highly unusual for a commissioner and bears more of a resemblance to the arrangements used for outside “special advisers” brought in to carry out defined and time-limited tasks.

Before taking up his responsibilities, Sir Julian will need to go through a gruelling confirmation hearing before MEPs. While the parliament does not per-se have a binding say on his appointment, Mr Juncker is required to “seriously consider” its views.

Gianni Pittella, the leader of the European Parliament’s centre-left Socialists and Democrats, told the Financial Times that he did not expect Sir Julian to face problems in his confirmation hearing.

“It is a little, technical portfolio,” he said of Sir Julian’s new role, adding that it would not have made sense to give the UK commissioner a larger job seeing as the country was heading for the EU exit door. There should be “no prize, no award” for voting to leave the EU, he said. The commission said the hearing was expected to take place in early autumn.