Abu Dhabi's government has hired Bain & Co and Landor Associates to advise on the merger of two of the emirate's biggest sovereign funds, a source familiar with the matter told Reuters.

In late June, Abu Dhabi announced it would merge Mubadala Development Co and International Petroleum Investment Co and had formed a committee led by Deputy Prime Minister Sheikh Mansour bin Zayed Al-Nahayan to oversee the process.

The combined fund would have assets worth around $135 billion, according to Reuters calculations based on both funds' latest financial statements.

The source, who declined to be named, said both advisers had signed contracts, with Bain, a global management consulting firm, handling the area of business strategy and Landor, a US-based brand consulting firm, serving as branding adviser.

Because the common shareholder is Abu Dhabi and neither fund is publicly traded, it is unlikely that there will be an outside financial adviser for the merger, the source added.

The merger, which Abu Dhabi says will increase the emirate's investment power and revenues, is expected to be completed by the end of 2017. - Reuters