Bosses at an oil firm whose rig ran aground on the Western Isles 10 days ago have admitted it is "tricky to predict" when the large structure will be refloated.

Specialist equipment is expected to arrive on the Isle of Lewis for tests to be carried out on Friday, although officials planning the recovery of the Transocean Winner said work could only be carried out if the weather and tides were in their favour.

The platform remains at Dalmore beach on the western side of the island after it was blown ashore with 280 tonnes of diesel on board last week.

The semi-submersible rig was being towed from Norway to Malta when it detached from its tug in bad weather in the early hours of August 8.

Two of its four fuel tanks were damaged in the incident, resulting in the estimated loss of 53,000 litres of fuel, most of which is thought to have evaporated.

Around 100 residents attended a public meeting on Thursday evening at nearby Carloway, where officials updated residents on the ongoing salvage operation.

Dave Walls, operations director with Transocean thanked the community and emergency services for their help.

"The other thing I would like to do is to apologise for the disruption to your daily lives," he said.

The meeting was told good progress is being made in the operation to refloat the structure, but it remains "tricky to predict" when that can actually take place.

Mr Walls said much has already been accomplished by the 15 people who are now working aboard the rig, with emergency generators, pumps and internal cameras among the systems already up and running.

But with the compressors needed to refloat the structure set to arrive on the island by ferry on Friday, officials cannot yet confirm when the rig will actually be removed from the beach.

Mr Walls said: "We need to get ourselves in the position where we're ready to float and we're not there yet.

"Once we're ready to float we then need the ideal conditions to float and that's a suitable weather window, no wind, the right tide.

"Everything needs to be just right because we get one opportunity to do it right."

He vowed that no trace of the rig would be left when the salvage operation - including a sweep of the seabed - is complete.

Work to transfer the diesel which remains on board the rig began on Thursday and is set to continue.

Fishermen are seeking compensation for loss of earnings, saying there would normally be vessels operating in the zone area to catch lobster and crab during the busy summer season.

Hugh Shaw, the Secretary of State's representative for maritime salvage and intervention overseeing the operation, said good progress has been made since that team boarded the rig on Sunday.

He added: "There has been no risk to life with this job so the next priority we have is protecting the environment.

"There is still diesel on the installation so we're making every effort to get that to a safe place on the rig as soon as possible."

A Marine Accident Investigation Branch investigation was launched into the incident. MAIB officials left the island on Friday, the meeting was told.

Don Mackay, chairman of Carloway Community Association, hit out at what he said was "top-down communication" from officials and warned it risked generating hostility towards those working hard at the oil rig.

It comes after an earlier community meeting, on Monday this week, was not attended by various parties, including the rig's owners and the official overseeing the operation.

Mr Mackay, who was in the audience at Thursday's public meeting in Carloway, told the panel: "We urge you on the platform to engage with us please in a meaningful two-way dialogue that will keep us informed at all times about what is happening down at the oil rig."

Mr Mackay's comments were met with applause from some members of the audience.

Earlier in the meeting, Mr Shaw had told the audience that there was "insufficient information" to pass on to them earlier in the week.

He added: "We felt we'd be much better placed to push the meeting back later in the week and we would be able to bring the full team along and give you a lot more detail."