Nearly 120 people have now been linked to a Covid outbreak on board the Shell Shearwater production hub in the North Sea.
Last week the operator confirmed 15 positive cases had been identified since June 30, with 85 workers identified as close contacts flown ashore.
The operator said the number of positive cases has now climbed to 20 with 98 close contacts, all of whom have either been evacuated or are in isolation waiting to leave the rig.
Testing has been taking place on the Safe Zephyrus flotel, which is bridge-linked to the Shearwater production facility in the central North Sea.
A turnaround of the platform is currently underway, meaning production has not been impacted.
Shell confirmed last week that testing has been taking place prior to all workers mobilising offshore, with additional tests every four days on board the Safe Zephyrus.
The firm said: “We are taking all appropriate precautions, in line with our procedures and national protocols related to coronavirus.”
Shearwater, 140miles east of Aberdeen and a hub for several neighbouring North Sea fields, had nearly 60 close contacts linked to an outbreak on board in April.
It comes after Taqa confirmed yesterday that 18 people on its North Cormorant platform had been linked to two separate positive Covid cases.
Taqa said the company carries out pre-mobilisation testing for everyone travelling offshore and that testing is carried out on board for anyone displaying symptoms.
Despite testing and rollout of vaccines, rising cases of the virus are putting pressure on hospitals.
Last week Aberdeen Royal Infirmary, Raigmore Hospital in Inverness and Dr Gray’s in Elgin were put on “code black” status as cases stretched the facilities to capacity.
Over the weekend, Scottish health secretary Humza Yousaf said Scotland is past the “worst of the peak” after the country was dubbed the “Covid Capital” of Europe.