Salvage experts, working at the Transocean Winner site, have still established no timescale for the safe towing of the stricken rig.
The official in charge of the recovery operation on the Isle of Lewis confirmed yesterday significant work has been carried out since salvors boarded on Sunday.
Hugh Shaw said that compressors were being transferred onto the rig, while towlines have also been attached to the installation.
The Maritime and Coastguard Agency revealed that the rig’s owner, Transocean, was transferring diesel fuel to tanks above the waterline, adding that recent checks had not revealed any pollution in the area.
But while progress has been made, salvors are still unsure when the rig will be ready for towing, nearly two weeks after it washed up at Dalmore beach on the western side of the island.
Mr Shaw, the Secretary of State’s representative for maritime salvage and intervention, warned of the danger of losing the rig again if towing begins without a clearer picture of the damage suffered to its buoyancy tanks.
Remotely-operated vehicles have been assessing the structure underwater, but it is only once compressors have been hooked up that salvors will know whether the rig can be made buoyant.
If it can’t be safely refloated and towed, Mr Shaw said the team would have to “sit down, take stock and see what the other options are”.
He added: “We don’t want to tow the vessel and have insufficient buoyancy. We do not want to lose the rig. If the salvage team don’t think they can do it, they’ll come back to me.”
He also vowed to keep local residents informed about the operation’s progress and attended a public meeting on Thursday night in nearby Carloway along with officials from Transocean.
Don Mackay, chairman of Carloway Community Association, claimed people felt they had been “ignored” in the wake of the rig’s grounding.
But Mr Shaw responded: “As soon as I am in a position to share when (towing) is going to happen, I’ll do so.
“The community has been supportive of us in our work and we, in return, have done our utmost to make sure they know what we’re doing and how and when.”
Transocean representatives apologised to residents for any disruption caused by the rig’s grounding and pledged to remove it without leaving a trace.