SEOUL, South Korea – Iran has agreed to rescue the 19-strong crew from a confiscated ship flying the South Korean flag, both countries announced on Tuesday. This appeared to be the first significant gesture by the Iranians, which de-escalated the problem since the ship was seized a month ago.

The Iranian move may also have been intended to send an indirect signal to the Biden administration, suggesting that it should avoid further deterioration in relations with Iran after it deteriorated sharply under former President Donald J. Trump to have.

In return for releasing the occupation, the South Korean government said it had pledged swift action to address Iran’s complaints about its inability to access $ 7 billion in Iranian funds due to US sanctions reimposed by Mr Trump were frozen to fix.

It was not immediately apparent from the announcement when the crew members would be released. Iran said the ship and its captain would remain in custody pending an investigation into the reasons for the ship’s seizure, cited by Iranians as violating the Maritime Pollution Act.

The ship, the Hankuk Chemi, loaded with 7,200 tons of chemicals, was taken into custody by the Islamic Revolutionary Guard Corps on January 4 while on patrol in the Persian Gulf. South Korea strongly protested the seizure and the shipowner called Iran’s allegations absurd.

It soon became clear that Iran had at least partially taken into custody of the ship in an attempt to pressure South Korea, a strong American ally, over the sanctions ordered by Mr Trump after breaking on the nuclear deal between Iran and the major world powers 2015 had waived. These sanctions included blocking Iran’s access to Iranian oil revenues in the billions that were deposited with foreign banks.

Iran began disregarding its nuclear deal obligations in response to Mr Trump’s actions and threatened further steps that may include blocking international nuclear inspectors from visiting nuclear sites.

While President Biden has said he wants to rejoin the nuclear deal if Iran resumes compliance, Iran has said the United States should drop sanctions first. Neither side has publicly shown an immediate readiness to find a diplomatic solution.

Iran’s approval of the liberation of the South Korean ship’s crew, which Saeed Khatibzadeh, a State Department spokesman, described as a humanitarian gesture, however, appeared to offer a degree of flexibility on sanction-related issues.

“This could be a signal to show a willingness to resume discussions or at least ease tension and perhaps open the door to South Korea to release seized Iranian assets,” said Farhad Alavi, partner at Akrivis Law Group. a Washington-based company specializing in sanctions law.

“Likewise, I wouldn’t be surprised if President Biden were to lift or suspend less sensitive or perhaps more political sanctions from the Trump era in the coming weeks or months – something more symbolic than essential,” said Alavi.

There was no immediate comment from the Biden administration on the news about the South Korean crew members.

The South Korean Foreign Ministry said in a statement that the decision to free the crew members was taken during a telephone conversation on Tuesday between Iranian Deputy Foreign Minister Seyed Abbas Araghchi and his South Korean counterpart Choi Jong-kun.

The crew consists of four South Koreans, and the other members are Burmese, Vietnamese and Indonesians, the statement said.

Mr. Choi welcomed the Iranian decision and called on the Iranian government to release the captain and ship as well.

During his telephone conversation with Mr. Araghchi, Mr. Choi promised “swift” action to deal with Iran’s complaints about the $ 7 billion confiscated.

Mr. Choi also told Mr. Araghchi that South Korea would consult American officials in Washington on the matter, the department said.

Choe Sang-hun reported from Seoul and Farnaz Fassihi from New York. Rick Gladstone reported from Eastham, Mass.