Britain has frozen all official bilateral contacts with Iran until all of its 15 detained naval personnel have been released, the British foreign secretary said earlier Wednesday.
London still has no idea about the whereabouts or the condition of its 15 captured sailors, one of whom was a woman.
"The servicewoman arrested by Iranian authorities together with UK Navy officers will be released today or tomorrow," he said.
The British Ministry of Defense has received information proving that 15 Navy personnel were 1.7 nautical miles (3.1 kilometers) inside Iraqi waters when they were seized last Friday.
British Vice Admiral Charles Style said the Ministry of Defense "unambiguously contested" Iran's claims that the Royal Navy personnel had strayed into Iranian waters.
Style said the seizure was "unacceptable, wrong and illegal."
The British Ministry of Defense said Iran detained 15 Royal Navy sailors and marines from HMS Cornwall in Iraqi territorial waters, which in accordance with a UN Security Council mandate under Resolution 1723 was inspecting ships in the Persian Gulf.
Following Britain's claims Iran's embassy in London issued a statement in which it said the sailors and marines had been 0.5 km inside Iranian waters at the time.
Iran's Foreign Ministry accused the Royal Navy of illegally entering Iranian territorial waters.