A multi-team operation to herd a pod of whales stranded in shallow water near Helensburgh to safety is continuing this evening - after the first rescue attempt failed.

Experts from the Ministry of Defence have been working alongside members of the British Divers Marine Life Rescue (BDMLR) organisation to try to safely move three northern bottlenose whales out of the Gareloch, where they have been for the past week.

The rescue operation began this morning (Thursday) amid growing concern for the animals' welfare, however first efforts to move the mammals came unstuck after the pod broke off at the Rhu narrows and headed back towards Garelochhead.

An update shared on the BDMLR Facebook page shortly before 5pm said: "The whales were successfully herded towards the mouth of the loch earlier today, however as the whales reached Rhu Point, they changed direction and headed back towards Garelochhead.

READ MORE: Wildlife group 'hoping for the best' as Gareloch whales rescue operation begins

"The boats have stopped to refuel and regroup, the operation will then continue.

"With an increasing amount of traffic on the water our spotters on shore are finding it difficult to monitor the movement of the animals."

NATO military exercise, Joint Warrior, is set to start this weekend, bringing with it an influx of vessels to the Faslane naval base over the next few days, and the MoD has said that it would be prepared to amend the scheduled programme of activity if circumstances involving the whales dictate.

We'll bring you the latest updates when we have them.