An American global insurance conglomerate has signed a deal this week to move into a new office block in the City of London which is still under construction.

The Liberty Mutual Insurance group in Boston is taking over several storeys of the tower block being built by Canary Wharf Group at 20 Fenchurch Street, near Aldgate.

It will occupy 117,000 sq ft of offices on the 10th, 11th, 12th, 21st, 22nd and 23rd floors when the building, which was ‘topped out’ in January, is completed in just over a year’s time.

One of Mutual’s subsidiaries moving in next year is Liberty Syndicates, whose president Nick Metcalf explained: “This iconic building enables us to be close to Lloyd’s and our brokers and clients.”

The complex is a joint venture between Canary Wharf and Land Securities Group. The letting follows a move by RSA in January to lease out its existing London premises and move to 20 Fenchurch Street when it is completed in 2014.