The John Fredriksen drilling company is making the move after it acquired 12.2m shares in Oslo-listed AOD after the close of trading on Thursday.

The shares were acquired at $5 each and lift Seadrill’s stake in the Thai-linked company to 25.7m shares, or 64.23%.

As a consequence, Seadrill said it will proceed with the launch of a mandatory cash offer for the remaining shares in the company.

Such a mandatory offer will be launched as soon as practicably possible, within the time limits set out in the Norwegian Securities Trading Act, Seadrill said.

Norwegian investment bank RS Platou Markets is acting as financial advisor to Seadrill in connection with the offer.

AOD has three KFELS Mod V – B class jack-up rigs under construction at Keppel FELS in Singapore for delivery by the third quarter of 2013.

The other major shareholder in AOD is Singapore-listed Mermaid Marine, which in turn is controlled by Thoresen Thai Agencies.

In a separate development Friday also saw AOD announce that it had secured a charter for its first newbuilding jack-up.

An unnamed company has agreed to take the AOR-1 for three year period for $197m plus a $39.5m mobilization fee.

AOD said the charter, which also includes a one-year option, was been entered into and will be managed by Seadrill on its behalf.

The rig is under construction at Keppel FELS in Singapore is due for delivery in March 2013 and is due to start the charter in June 2013.