On July 4, the Gibraltar Royal Police and Customs and Port Authority seized the Iranian tanker Grace 1 in the Mediterranean Sea, suspecting that it was en route to an oil refinery in Syria. The refinery, at the other end of the Mediterranean, is subject to European Union sanctions against Syria in force since late 2011.

The 24 Indians who were part of the crew on board the Grace 1 are "safe and well" and have since been granted consular access, the foreign ministry said. "We had sought consular access and it was granted yesterday (Wednesday). A three-member team visited and met all the crew members," said Raveesh Kumar, the foreign ministry spokesperson.

The Indian High Commission in London said that that further meetings with Gibraltar officials are planned later this week. "All help will be extended to the Indian nationals," the High Commission said in a statement.

On Friday, Iran's Islamic Revolutionary Guard Corps seized the UK-flagged tanker Stena Impero, surrounding it with attack boats before troops rappelled onto its deck from a helicopter. The ship had a crew of 23 out of whom 18 were Indians. The tanker was impounded for allegedly breaking "international maritime rules".

India has asked Tehran to provide consular access to the Indian nationals. "We have requested for the early release and repatriation of 18 Indians who were detained off the Iranian coast. We have sought access and we do hope access will be granted very soon. We continue to impress upon Iranian authorities to release them so that we can begin the process of repatriation," Mr Kumar said on Thursday.

Images from inside the ship released by Iranian authorities on Monday showed some Indian crew members sitting around a table, chatting and smiling. Two members could be seen cooking in the ship's kitchen.

Iran has hinted that it is open to a tanker swap -- releasing the Stena Impero in return for its oil tanker, Grace 1, being allowed to proceed.

The Gibraltar authorities have claimed that the Grace 1 is loaded to capacity with crude oil en route to Syria and confirmed that the next hearing in the case is scheduled for August 15.

Tehran blames the US for arranging to have its ship seized in the wake of sanctions imposed against Iran with the aim of halting all its oil exports.