Owner: Detention of UK-flag Tanker Unacceptable

The continued detention of British-flagged tanker Stena Impero is "unacceptable and unjustifiable" and there are concerns for the welfare of the crew after 19 days in confinement, the vessel's owner said on Tuesday.

Iran's Revolutionary Guards on July 19 seized the Stena Impero in the Strait of Hormuz waterway for alleged marine violations. That came 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.

The saga has exacerbated frictions between Tehran and the West since the United States pulled out of an international agreement curbing Iran's nuclear programme and reimposed economic sanctions.

Stena Bulk's chief executive and president Erik Hanell said the company had limited communication with the crew onboard.

"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," he said in a statement.

The vessel's 23 seafarers are of Indian, Russian, Latvian and Filipino nationality, the company has said.

Hanell said a Finnish consulate visit to the vessel, on behalf of Latvian authorities, took place on Aug. 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," Hanell 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.

Iranian President Hassan Rouhani warned on Tuesday that shipping might not be safe in the Strait of Hormuz, adding that "war with Iran is the mother of all wars".

Britain on Monday 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. That gives crew members the right to refuse to work onboard British-flagged vessels traversing the waterway.

The cost of insuring a ship sailing through the region has risen tenfold as risks have risen, which has also prompted some ship owners to avoid the area entirely.

Reporting by Jonathan Saul