Iran's state broadcaster has aired a video showing for the first time the 23-member crew of the British-flagged ship seized by Iran.
In the video aired on Monday, the Stena Impero crew is seen dressed in red uniforms and seated around a table onboard the vessel as an unidentified Iranian man is heard thanking them for their co-operation.
A cameraman is heard telling them not to look at the camera.
It wasn't clear if the crew was under duress to take part in the filming.
Other shots show a man checking on the ship, the crew sharing a laugh and talking next to a coffee machine inside the ship.
The crew's chefs are seen preparing food. Another video, also released by Iran's state broadcaster, shows Iran's flag hoisted on the ship's bridge.
The footage came as the Iranian embassy in India said all crew members were safe and still on the vessel.
"All the crew members including the Indian nationals are in good health, they are still on board the tanker," the embassy told Reuters on Monday.
Eighteen of the Stena Impero's 23-strong crew are Indian nationals, Iranian authorities said previously.
The crew also includes Filipino, Russian and Latvian nationals.
The family of one Indian crew member - 26-year-old mess worker Dijo Pappachen, who joined the vessel just a month ago - said the company operating the tanker had told them about the sequestration on Friday.
"Neither has Dijo contacted the family nor could we contact him after the tanker was captured," his tearful father Pappachen TV said in their home town of Kochi in southern India.
Britain called on Iran on Monday to release the tanker and its crew immediately, describing the seizure as illegal.
European countries including Britain have stuck with the nuclear pact that Iran signed with world powers in 2015 after the United States pulled out last year.
But the pact is now hanging by a thread and Britain was thrust more directly into the confrontation on July 4, when its Royal Marines seized an Iranian tanker, the Grace 1, off the coast of Gibraltar.
Britain accused it of violating sanctions against Syria, prompting repeated Iranian threats of retaliation.
Grace 1 also had Indian crew, who are now in British custody.
The brother of that ship's junior officer KK Ajmal told Reuters from their hometown in Malappuram in southern Kerala that they exchanged voice notes via social media on Sunday .
Mohammed Shareef said his 27-year-old brother told him the captain and the engineer were separated from the rest of the crew after British commandos took over the vessel.
Ajmal said he and the other crew were getting food, water and other essentials.
The ship had been sailing from the port of Fujairah with 300,000 tonnes of crude oil when British commandos forced it to stop and came aboard in 10 helicopters, Shareef quoted his brother as saying.