The operator of the British-flagged tanker seized by Iran has made contact with the crew.
Stena Bulk said the master of the Stena Impero had "advised that everyone was safe with good cooperation with the Iranian personnel onboard".
Erik Hanell, Stena Bulk president and CEO, said: "We do of course appreciate this step of development and that this is a first sign that we will soon see more positive progress from the Iranian authorities."
Stena Bulk said the crew's family members were being kept updated on the latest developments and being offered the firm's full support.
The British-flagged vessel was taken by Iran's Revolutionary Guard on Friday amid heightened tensions between Tehran and the West.
Tehran released pictures of the 23-strong crew - including nationals from India, the Philippines, Russia and Latvia - at the weekend.
The men could be seen sitting cross-legged on the bridge having had their shoes removed and piled up.
The outgoing Prime Minister Theresa May chaired a meeting of Whitehall’s Cobra emergency committee on Monday morning on how to respond to the escalating crisis.
The development on Monday came as the head of the Iranian supreme leader's office said the UK was sending a mediator to negotiate for the release of the vessel.
"A country that at one time appointed ministers and lawyers in Iran has reached a point where they send a mediator and plead for their ship to be freed," Mohammad Mohammadi-Golpayegani said, according to the semi-official Tasnim news site.
The issue will be one of the first diplomatic challenges confronting incoming prime minister Boris Johnson.
Tehran has claimed the tanker collided with a fishing boat, while the UK has accused Iran of "state piracy".
