The hunger strike by Richard Ratcliffe outside the Iranian embassy in London is making work there impossible and putting pressure on diplomatic staff, Iran’s ambassador to the UK has said.

Ratcliffe, the husband of the imprisoned Iranian-British dual national Nazanin Zaghari-Ratcliffe, began the protest last weekend and has been visited by a growing number of family members, supporters and politicians, including SNP MPs and Labour’s deputy leader, Tom Watson.

Tired but in good spirits and surrounded by flowers and signs, Ratcliffe said on Thursday he would continue at least until the weekend, when he would speak to his wife about the steps she wished him to take next.

He said it had been the decision of the Iranians to erect two large corrugated iron barriers in front of the entrance to the embassy opposite Hyde Park. The ambassador, Hamid Baeidinejad, said they were designed to shield staff from being filmed.

Nazanin Zaghari-Ratcliffe's husband: I will join hunger strike for as long as I can Read more

In an apparent reprisal for the protest, some of the diplomatic protection provided for the British embassy in Tehran has been removed.

Watson expressed solidarity with Ratcliffe. “His family is trapped in a terrifying geopolitical game,” he said. “I urge the Iranian government to assist the de-escalation of military tension and release Nazanin as an act of humanity.”

Zaghari-Ratcliffe is serving a five-year sentence for espionage and is on hunger strike in Tehran in protest at her conditions.

Baeidinejad, at a briefing called in part to discuss the growing crisis in the Gulf, said of Ratcliffe: “He is now blocking the entrance of our embassy and the peace of mind of our staff is in complete despair.”

He said the door of the embassy was blocked because of the action. “There are media cameras 18-19 hours a day focusing on the entrance of the embassy, so any person going in and leaving is filmed which is totally unacceptable,” he said, adding that all meetings were being cancelled as a result.

Baeidinejad said he had raised with the Foreign Office his concern that Ratcliffe’s activities were in breach of article 22 of the Vienna convention, which protects the ordinary daily activities of the embassy.

“Every citizen has a right to express his opinions and we respect the right to demonstrate but there is a place designated on the other side of the street and Mr Ratcliffe can go there. He can see the embassy and the Iranian flag from there,” he said.

“We do not understand why there should be an exception for Mr Ratcliffe, why there should be discrimination and why he has selected just to be in front of our embassy which is blocking our entrance.”

Staff were being insulted and intimidated, Baeidinejad said. “His presence is disrupting the work of the embassy and apparently what he has in mind is a campaign of pressure against the embassy.

“We have sympathy with him because we know that he is a father and a husband. We are sorry about this situation but this situation has occurred by the wrongdoing of a national lady and she has a verdict of five years in prison. We know it is difficult for a mum to be separated from a kid. Of course, there are frequent visits by the kid, and we have done our best to ensure there are no difficulties in the life of the daughter.”

He said Ratcliffe was free to go to the embassy and apply for a visa, but he did not say whether a visa would be granted.

“We have always been discussing with the judiciary how they can provide better health facilities and we are happy that the concerns have all been met,” Baeidinejad said.

“We are trying our best to accommodate the concerns of the family. He is raising only one demand which is the immediate release of the mother, but the judiciary is the body that makes the final decisions of this. This cannot be done by pressure or political manoeuvring. This is the law and the judiciary should make proper decisions.”