Royal Gibraltar Police have announced that the arrested crew members of supertanker, which carried Iranian crude oil, have been released.

The four released crew members, which include the ship's arrested captain along with three officers, were granted conditional bail as investigations surrounding the tanker continue, according to a police statement on Friday.

The released crew, all of which are Indian nationals, had been arrested during the past two days.

Iran and Britain have been locked in a diplomatic dispute since July 4, when Gibraltar’s police, aided by a detachment of British Royal Marines, seized the Grace 1 tanker on alleged suspicion of carrying crude oil to Syria, which has been under EU sanctions.

Spain, which challenges the British ownership of Gibraltar, has, however, said the seizure was prompted by a US request to Britain and appeared to have taken place in Spanish waters.

Gibraltar has yet to announce the fate of the ship and its crew after the territory’s Supreme Court set a 14-day deadline last week for the country’s authorities to conduct “investigations” about the ship.

Iran has condemned the seizure as “maritime piracy,” vowing to employ all its political and legal capacities to secure the release of the vessel and uphold its rights.

'Dangerous game'

Speaking on Friday, Iranian Foreign Ministry spokesman Abbas Mousavi also rejected claims about the supertanker's alleged route to Syria, adding that no Syrian port could receive a vessel of such capacity.

Mousavi added that evidence presented by the British had shown that the allegations were legally insignificant.

The Iranian spokesperson warned London from entering "a dangerous game under the influence of the Americans with no end in sight.”

Earlier this week, Iranian Foreign Minister Mohammad Javad Zarif also slammed the seizure as "pure piracy" done on behalf of the "B-team", a term used by the minister to describe a quadruple of leaders widely believed to be influential in shaping Trump's campaign of "maximum pressure" against Iran.

Zarif further added that London's allegations about the tanker breaching EU bans on Syria were irrelevant since “Iran is neither a member of the EU nor subject to any European oil embargo”.

“Last I checked, EU was against extraterritoriality," he added, warning that the measure would set “a dangerous precedent and must end now.”

British officials, including British Foreign Secretary and Tory leadership candidate Jeremy Hunt, have claimed that they do not want tensions with Iran to "escalate".

However, marking a further escalation with Iran, Britain alleged on Thursday that Iranian speedboats had sought to block the passage of one of its tankers in the Persian Gulf, but backed off after warnings were issued by a British military vessel.

Iranian authorities dismissed the allegations later on Thursday, with the IRGC issuing a statement rejecting any encounter with foreign ships “in the past 24 hours”.

Following the alleged confrontation, the British government announced on Friday the deployment of a second British warship to the Persian Gulf in order to ensure "freedom of navigation" in the vital international shipping route.

The newly deployed ship, HMS Duncan, will operate alongside HMS Montrose for a short period before HMS Montrose docks in Bahrain for maintenance.

The deployment had been planned before tensions escalated with Iran, according to British sources.

Speaking on Friday, Mousavi rejected the presence of any foreign forces in the Persian Gulf, stressing that the region's security has to ensured by the cooperation of neighboring states in the region.

"Any presence of foreign forces, which come from tens of thousands of kilometers away and on the false pretext of ensuring regional stability, is unconstructive and should alarm everyone," he said.