Julian Assange has been called a “miserable little worm” by a British foreign affairs minister, who says it is “about time” that the WikiLeaks founder gave himself up to British justice.

Alan Duncan said on Tuesday local time it is of “great regret” that Mr Assange is still living inside the Ecuadorian embassy in London, since he entered the building to avoid extradition to Sweden to face questioning about allegations of sex crimes in June 2012.

The Swedish investigation was dropped in May 2017, but Mr Assange, who was on bail when he walked into the embassy, faces arrest by the British authorities for breaching his bail terms should he step outside.

The Europe and the Americas minister also criticised tweets posted by Mr Assange on Monday night in which he claimed the “manner” and “timing” of Russian diplomatic expulsions had been “poor diplomacy”.

During Foreign Office questions in the Commons, Mr Duncan was asked to take action against the Ecuadorian embassy by former cabinet minister Patrick McLoughlin.

“Just how long are we prepared to allow this situation to go where, as the Minister of State said at the last questions, a man is avoiding lawful arrest?” Mr McLoughlin asked.

“It is of great regret that Julian Assange remains in the Ecuador embassy,” Mr Duncan replied.

“It is of even deeper regret that even last night he was tweeting against Her Majesty’s government for their conduct in replying to the attack in Salisbury.

“It’s about time that this miserable little worm walked out of the embassy and gave himself up to British justice.”

Mr Assange, who has always denied allegations of sexual crimes, responded to Mr Duncan’s comment with a tweet, saying he would rather be a worm than a snake.

As a political prisoner detained without charge for 8 years, in violation of 2 UN rulings, I suppose I must be "miserable"; yet nothing wrong with being a "little" person although I'm rather tall; and better a "worm", a healthy creature that invigorates the soil, than a snake.

— Defend Assange Campaign (@DefendAssange) March 27, 2018

In an email to Reuters, Mr Assange questioned why there is still a warrant for his arrest, as he considers himself to be under arbitrary detention in the Ecuadorean embassy.

“I have already fully served any theoretical (I haven’t been charged) ‘bail violation’ whilst in prison and under house arrest. So why is there a warrant for my arrest?” he said.

The description of his situation has been rejected by the British authorities, who say he voluntarily put himself in this position by entering the building and that he could leave at anytime.

-with wires