Flying restrictions caused by volcanic ash from the Icelandic eruption has led to NorthLink Ferries putting on an extra round trip between the Shetland Isles and Aberdeen over the weekend.

Shetland has been left particularly isolated because of the flight ban and NorthLink services have been the only means of arriving at or leaving the islands since the restrictions were imposed on Thursday.

NorthLink has experienced unprecedented, last-minute demand for places on its ro-ro ferry Hrossey. At three o'clock on Thursday afternoon there were still 122 places available on the 600-capacity vessel for Friday’s southbound sailing from Lerwick to Aberdeen via Kirkwall. By 9.00 this morning every berth was taken as the ferry company's web-site and booking office were inundated by travellers trying to make their way south.

Hrossey will depart Lerwick tonight at 5.30 and is scheduled to arrive in Aberdeen at 7.00 tomorrow (Saturday) morning.

The next timetabled northbound service would not have been until five o'clock on Sunday night. However, due to the flying restrictions placing travellers under extreme pressure it has been decided that Hrossey will turnaround almost immediately in Aberdeen and sail north for Lerwick at 9.00 am tomorrow (Saturday) morning. She is due to arrive in Lerwick at 9.00 pm. She will then turnaround almost immediately for a southbound sailing at 10.00 pm and will be due to arrive in Aberdeen at 11.00 am on Sunday morning.

Hrossey will then revert to scheduled service with a 5.00 pm northbound departure from Aberdeen on Sunday.

NorthLink chief executive Bill Davidson said: "The air restrictions imposed due to the volcanic ash have meant we've seen unprecedented last minute demand for our services. Our Customer Service Centre has never seen such a high rate of calls. Our staff have worked extremely hard to help all passengers and the extra sailings will help to ease the pressure which has been made even more challenging because we have one of our vessels away for annual refit in Birkenhead. We have been in regular contact with the Scottish Government as the volcanic ash problem has developed and this morning they have agreed to our suggestion of operating the extra services on Saturday."

Passengers who wish to make use of the extra sailing should book online - or call the NorthLink booking centre on 0845 6000 449.