Iran intends to again accuse the United States of violating the landmark 2015 nuclear accord between Tehran and world powers at next week's meeting on the agreement in Vienna, a senior Iranian diplomat said Wednesday.

"The U.S. is regularly violating the nuclear deal and this is a source of concern for Iran. Therefore, we will raise this issue in Vienna," Iranian Ambassador to Britain Hamid Baeidinejad said in an interview with Kyodo News in London.

On March 16, deputy foreign ministers of Iran and the so-called five-plus-one countries -- Russia, China, Germany, France, Britain and the United States -- will meet in the Austrian capital to review the implementation of the Iran nuclear deal and address concerns.

Tehran has recently accused European countries of taking a hypocritical stance regarding the deal and appeasing U.S. President Donald Trump.

Iran specifically believes that Washington is scaring European traders about the consequences of working with Iranian companies and it is necessary for the European Union to resolve the matter for the sake of the deal.

Since Trump entered the White House in January 2017, he has repeatedly criticized the Joint Comprehensive Plan of Action, calling it the "worst deal ever negotiated." He has also threatened to exit the deal.

Earlier this year, Trump said he will refuse to waive sanctions against Iran in May if his administration cannot reach an agreement with Europe.

Iran and the European Union have differences over some crucial issues including the former's ballistic missile program. Iran insists its missile program is defensive.

"All we have agreed is that nuclear deal has no link to the other issues," Baeidinejad said.

A day before the Vienna gathering, European powers will meet with American officials in Berlin.

"The agenda of the Berlin meeting is not to prepare for another negotiation over Iran's missile or regional issues. We have been assured that Britain's position in the Berlin meeting will be to convince the U.S. to keep adhering to the deal," he said.

"Britain has declared to us that they will have a very frank dialogue with U.S. and they will expect Trump's administration to adhere to its commitment in nuclear deal," he added.

Regarding the case of Nazanin Zaghari-Ratcliffe, a British-Iranian aid worker imprisoned in Tehran in 2016 for espionage, Baeidinejad said the Iranian Foreign Ministry is trying to find "exit avenues and legal ways for Zaghari-Ratcliffe to be released in the shortest time."

Britain has pushed hard for the release of the 38-year-old mother on humanitarian grounds.

Baeidinejad said her case involves "complicated" legal issues but that the judiciary is positively looking at the humanitarian aspects of it, adding that no date for her release has been scheduled.

Iran and Britain severed diplomatic ties in 2011 after a group of hardliners stormed the British Embassy in Tehran. In 2016, diplomatic relations were restored to their pre-2011 level, with Baeidinejad, a senior Foreign Ministry official, being appointed ambassador in London.