Dyfrig Siencyn has resigned as the leader of Cyngor Gwynedd amid a row over the inquiry into disgraced headteacher Neil Foden.

Four councillors resigned from the council's cabinet last week after Mr Siencyn refused to apologise to Foden's victims in an interview with Newyddion S4C.

Mr Siencyn's deputy, Nia Jeffreys, has been appointed as interim leader until a successor is found.

Foden, a former executive headteacher at Ysgol Friars in Bangor and Ysgol Dyffryn Ogwen in Bethesda, was jailed for at least 17 years for sexually abusing four girls.

According to a BBC Wales TV documentary, it was claimed Foden may have abused four times as many victims as previously thought, with allegations dating back to 1979.

Mr Siencyn, who also resigned as leader of the Plaid Cymru group, told Newyddion S4C he did not back calls from senior members of his party for a public inquiry, but later retracted his remarks and apologised to "all those who suffered".

His initial interview led to the resignations of Beca Brown, Berwyn Parry Jones, Dafydd Meurig and Elin Walker.

In a statement on Thursday lunchtime, Mr Siencyn said: "I must acknowledge that this most recent period – and the horrific information which has come to light about the unforgivable crimes of the paedophile Neil Foden – has been the most challenging for the council as an authority and for myself as leader."

"I am deeply sorry for the pain the victims and their families have gone through at the hands of this man, and they remain at the forefront of my mind.”

He also defended his seven-year record in office as leader of the council, adding: "I look back with pride at what we have achieved here at Cyngor Gwynedd over the past seven years."

"In particular, pioneering work has been done to secure homes for local people and to better manage second homes within the county; we have invested significantly in school buildings; UNESCO status has also been secured for our slate areas, resulting in significant funding which will bring new prosperity to these communities."

"It is also important to remember the heroic work done by the army of staff from across the council, partners from the third sector, volunteers and communities to support the people of Gwynedd through the Covid crisis."

"I am also pleased that Cyngor Gwynedd has taken decisive action to safeguard our most vulnerable residents from the devastating effects of the cost of living crisis, while at the same time protecting key services from wave after wave of budget cuts."

Mr Siencyn, who is a ward councillor in North Dolgellau, is also stepping down from his roles as chairman of the Ambition North Wales Board and the Welsh Local Government Association (WLGA) finance sub-group and co-chair of the Wales Rural Forum.

Cllr Beca Roberts, chair of Cyngor Gwynedd, added: "I pay tribute to Councillor Dyfrig Siencyn for his work in leading the council since 2017 and for being a strong and consistent voice for Welsh-speaking and rural communities regionally and nationally."

"I thank him for his friendship, experience and unwavering leadership over the years. I am sure he will have a further contribution to make to the work of the council and to the public life of Wales in future."

Cllr Nia Jeffreys, the deputy leader and cabinet member for economic development, will take charge until members elect a new leader at a later date.

Reacting to the resignation, Welsh Conservative leader Andrew RT Davies said: “I believe this resignation is the right decision. The victims should be at the very centre of this case, and their pain will stay with them."

“There must be a full inquiry to establish how Foden was able to get away with his appalling crimes for so long.”