The UK government on Saturday named two Britons detained in Iran as Craig and Lindsay Foreman, with their family saying they are determined to ensure the pair's "safe return."

The two are currently being held in the city of Kerman, the family said in a statement issued by the British foreign ministry.

"This unexpected turn of events has caused significant concern for our entire family, and we are deeply focused on ensuring their safety and well-being during this trying time," they said.

The family added that it was "united in our determination to secure their safe return."

"We truly appreciate the outpouring of support from friends, family, and the community, which has provided us with strength and encouragement as we face this ordeal," said the statement.

The couple are in their early 50s and were on a motorbike tour around the world when they were detained in January.

Britain's Foreign Office confirmed on Friday that it was "providing consular assistance to two British nationals detained in Iran" and was in contact with Iranian authorities.

That came after Iran's official news agency IRNA reported on Thursday that two British nationals were being held in central Kerman province for unspecified security offences.

The UK government advises against all travel to Iran.

It says British and British-Iranian dual nationals are "at significant risk of arrest, questioning or detention."

Several other Europeans are held in custody in Iran, which has conducted multiple prisoner exchanges with Western governments in recent years. (AFP)