The body which runs the Senedd says it is embarking on its "most complex ever project" as it prepares to relocate staff and politicians while refurbishment work is carried out on their existing offices.

The Senedd Commission has been considering how to proceed when its lease on the Tŷ Hywel building - situated directly behind the Senedd - ends in 2032.

Its preference is to remain in a refurbished Tŷ Hywel, which would mean having to move staff into neighbouring accommodation until 2030.

A final decision is expected in December, with work scheduled to begin next year.

Details of the plan have been published as part of the Senedd Commission's annual budget proposals.

The commission is asking Members of the Senedd (MSs) to approve its request for a total budget of £109m for the 2027-28 financial year.

That marks an increase of 6.45% compared to last year's budget.

The sum includes £11.4m to cover costs linked to the potential Tŷ Hywel renovation, with that figure expected to rise to £16.6m in 2029-30.

The funding request follows previous increased budgets to cover the cost of preparing for an expanded Senedd, which included increasing the size of the debating chamber.

Much of the refurbishment work - including new windows and lifts - would be paid for by the building's owner Equitix.

It is expected to cost the public purse £42m over the next three years.

The "worst case" plan set out by the Senedd Commission would see all Tŷ Hywel users moved into alternative accommodation by summer 2027.

They would return in 2030 - the year of the next Senedd election.

Following the refurbishment the commission would have the option to buy the building or enter a 50-year deal which would allow it to purchase the site for £1 in 2082.

A Senedd Commission spokesperson said it had "taken prudent action to ensure the Senedd's long term office accommodation needs".

"The best-value-for-money option is the refurbishment of Tŷ Hywel by the building's owner.

"This will be a very substantial project and, if approved, may require the relocation of MSs, their staff and commission staff to nearby office space."

Tŷ Hywel is located directly behind the main Senedd building with two bridges allowing MSs and staff members to walk directly between both locations.

It has provided office space for Senedd staff and the media since 1998, ahead of the establishment of the National Assembly for Wales - as it was then called - a year later.

Before the Senedd building opened in 2006, Tŷ Hywel was also home to the main debating chamber.

The commission's budget document also plans for a 3.5% pay rise for staff in 2027-28 alongside a decrease in employer pension contributions, as well as a pay rise of 4% for MSs.

MSs salaries are set by the independent remuneration board.