S4C last night announced major changes to its management structure following the sudden departure of chief executive Iona Jones.

The Welsh-language channel said the changes would “lead to a closer working relationship” between the S4C Authority – the regulatory body that oversees S4C’s performance – and a “leaner” management team.

It was not clear whether the changes were triggered by Ms Jones’ exit, or if they led to her leaving her post at the channel.

However, it is understood there were long-standing tensions between Ms Jones and the S4C Authority, chaired by John Walter Jones, which had grown in recent months.

Mr Jones yesterday said that the four executives on the new management team were Rhian Gibson, S4C’s director of commissioning, Garffîld Lloyd Lewis, director of communications, Elin Morris, director of corporate and commercial policy, and Kathryn Morris, finance and human resources director – who will take on the role of accounting officer.

Mr Jones said S4C will “work more closely with companies within the independent sector” so the future of the channel and its programme providers was “secure”.

That pledge comes after companies in the previously buoyant Welsh creative industries sectors, providing much programming for S4C, hit financial troubles.

Barcud Derwen, the TV facilities firm, went into administration last month, while it emerged this week that animation firm Calon TV had gone into liquidation.

S4C is facing serious spending constraints – the channel receives more than £101m a year from the UK Government, but has already been told to find savings of £2m this year.

Whitehall is understood to be considering making a further 6% cut in each of the next four years to S4C’s budget.

The channel said yesterday that meetings were taking place with directors of production companies with S4C aiming to meet all its production companies in the next few weeks.

Mr Jones said: “In order to ensure that the channel’s future remains secure and that the organisation is run efficiently, the most fundamental change is that the concept of due separation between the S4C Authority and the management team will now cease.

“S4C is a unitary body and this unitary organisation should manage and safeguard the interests of S4C viewers and the channel’s suppliers in the future.

“The management team’s organisational structure is also changing, with a smaller executive team working closely with the authority members. We will work closely to ensure that we strengthen the partnership between S4C and the programme suppliers.

“The channel’s future is secure, but we do face numerous challenges, just like other public service organisations. We are confident that we are robust enough to strengthen the channel in the face of the wholly digital television age.”

Labour AM Alun Davies, a former S4C executive, yesterday called for explanations from the channel.

He said: “S4C needs strong, strategic and far-sighted leadership. It is now very clear that there have been some significant tensions within the broadcaster and these tensions have prevented S4C from being effectively led for some time.

“The authority has a clear duty and responsibility to deal with these issues. At present they do not seem to be able to do so and this raises further questions about their role.”

Plaid Cymru MP Hywel Williams said: “The strategic direction of the channel is now obviously a matter for the channel itself, but I hope that at a time when S4C is threatened with substantial cuts by the Tories and Lib-Dems, a new chief executive is in post as soon as possible.

“S4C needs a strong leader to take the channel forward in such precarious times.”

Welsh Secretary Cheryl Gillan said: “I was concerned to hear reports of the departure of the chief executive from S4C. Having spoken to the S4C chairman John Walter Jones, I am reassured I will be kept fully informed on developments.

“I have also spoken with ministerial colleagues at the Department of Culture, Media and Sport. We remain fully supportive of S4C and the important role it plays within the broadcasting and creative industries in Wales.

“I look forward to ongoing discussions with S4C to ensure it continues to deliver quality Welsh language programming.”

It is now very clear that there have been some significant tensions within the broadcaster