21st Century Fox has doubled down on a series of guarantees to secure backing for its takeover of British-pay TV operator including increasing its commitment to Sky News.

The Hollywood studio has revealed that it has now offered to maintain a well funded Sky-branded news service in the UK for at least ten years, up on the five years if offered earlier this month. It has also stated that the commitment is no longer subject to Fox owning more than the 39.14% it currently owns in Sky.

In a letter sent by law firm Allen & Overy to the Competitions and Markets Authority’s Project Director Joel Bamford, it noted: “The duration of the commitment to maintain a Sky-branded news service has been amended from at least five years to at least ten years. Linked to this, in addition to maintaining the operational net investment in Sky News at a level not materially different from that set out [previously], 21CF shall also commit to a further five years of investment in Sky News at a level to be determined at the time, taking into account market conditions and the level of investment required to maintain a Sky-branded news service.”

This comes after the studio offered a number of initial “firewall remedies” on February 12, designed to safeguard the independence of Sky News.

The guarantees were made to the regulator, which last month provisionally ruled that the takeover raised media plurality concerns surrounding the Murdoch family. It comes as Fox has spent over a year attempting to buy the 61% in Sky, which is controlled by the Murdoch Family Trust, which also controls News Corporation, the publisher of British newspapers including The Sun and The Times, that it does not currently own.