Norwegian investor and tanker owner Frederik Mohn will become the biggest shareholder of Swiss rig and drillship group Transocean following its $1.2bn swoop for Songa Offshore.

Transocean has agreed to buy Oslo-listed Songa in a deal that creates an industry giant with more than 50 drilling assets. 

Songa chairman Mohn said: "The combination of Songa Offshore and Transocean is a strategic fit. The