Authorities in Gibraltar will decide on release of the Indian crew on board an Iranian oil tanker following due process of law. (photo credit: Reuters)

In the midst of its rising tension with Iran, the UK on Wednesday said it is for the Gibraltar government to decide on release of 24 Indian crew on board a seized Iranian oil tanker taking into consideration due process of law.

On July 4, British marines helped Gibraltar in detaining Grace 1, the Iranian tanker, which was reportedly carrying oil to Syria in violation of sanctions slapped against the Gulf nation by the European Union.

Two weeks later, Iran seized a British oil tanker near the Strait of Hormuz, further escalating the tension between the two countries. Eighteen Indians were on board the British ship Stena Impero.

"There is no question of a swap. This is not a game of swapping," British High Commissioner Dominic Asquith told journalists during a media interaction when asked there would be any link between release of 24 Indians on board Grace 1 and freeing of those on board Stena Impero.

The envoy said British marines had acted against Iranian ship as the oil it was carrying was being taken to a country which was facing EU sanctions which termed as "completely illegal".

"It is not for us to release the Indians on board Grace 1. It is for Gibraltar authorities to decide. They have their own judicial process," he said.

When asked about the reported comments by the Indian captain of Grace 1 that he did not know about the EU sanctions against Syria, Asquith said he was intrigued by the sailor's remarks.

Indian officials have met the 24 Indian crew members who were on board 'Grace 1' and assured them that the government will take necessary steps to ensure their release and repatriation, the External Affairs Ministry said last week.

Sources said 20 crew members may be repatriated to India soon while four may face judicial process in Gibraltar.

India had sought consular access to the Indians and it was granted on July 24.