There are mounting concerns over the welfare of the crew aboard a British-flagged ship seized by Iran, the vessel's owner has said.
The owner of the Stena Impero, which was taken in the Strait of Hormuz last month, also said its continued detention was "unacceptable and unjustifiable".
In a statement, Stena Bulk's chief executive and president Erik Hanell said the company had limited communication with the crew onboard.
He said: "Although they remain in good health considering the circumstances, we continue to be concerned about their welfare given the amount of time they have been in confinement."
The vessel's 23 seafarers are of Indian, Russian, Latvian and Filipino nationalities, the company has said.
Mr Hanell said a Finnish consulate visit to the vessel, on behalf of Latvian authorities, took place on August 3.
"The Finnish representative advised that the crew were in good health, however the duration of their confinement remains of considerable concern to the crew," he said.
"We want to emphasise the difficult circumstances they are enduring as a result of this ongoing situation."
The company said it had yet to receive an official answer from Iranian authorities over its request to visit the vessel.
Iran's Revolutionary Guards seized the Stena Impero on July 19 for alleged marine violations, two weeks after Britain seized an Iranian oil tanker near Gibraltar, accusing it of violating sanctions on Syria.
Britain has repeatedly ruled out any swap of tankers.
Iranian president Hassan Rouhani warned on Tuesday shipping might not be safe in the Strait of Hormuz and said that "war with Iran is the mother of all wars".
On Monday, Britain joined the United States in a maritime security mission in the Gulf to protect merchant vessels sailing through the Strait of Hormuz.
Last week, seafarers union Nautilus International said it had reached an agreement with the UK Chamber of Shipping trade association and the National Union of Rail, Maritime and Transport Workers (RMT) to designate the Strait of Hormuz a high risk area.
This gives crew members the right to refuse to work onboard British-flagged vessels traversing the waterway.
Meanwhile, the cost of insuring a ship sailing through the region has risen tenfold as risks have increased, which has also prompted some ship owners to avoid the area entirely.
Additional reporting by agencies.
