British Prime Minister Rishi Sunak on Tuesday reorganised several government departments and appointed a new Conservative Party chairman following last month's dismissal of a senior ally over murky tax dealings.

Sunak, who last week marked 100 days in 10 Downing Street, announced close confidant Greg Hands had replaced Nadhim Zahawi in the role of party head and cabinet minister without portfolio.

The Tory leader fired the wealthy Zahawi after an internal probe into his tax affairs -- dating from his founding of the YouGov polling company in 2000 -- found a "serious breach" of ministerial rules.

Hands, an MP for a west London constituency, said on Twitter he was "excited" to be the new Conservative party chair, a fundraising and coordinating role seen as crucial in the run-up to general elections.

"The work starts right away," he added.

Sunak also opted to create four new government departments, as he bids to turn around the government's currently dismal fortunes ahead of a general election expected next year.

The ruling Conservatives -- in power since 2010 -- are trailing the main opposition Labour party by wide margins, according to polls over recent months.

It follows several damaging scandals involving Sunak's predecessors and amid the worst cost-of-living crisis in a generation as decades-high inflations threatens to tip the economy into recession.

Sunak created a new Department for Energy Security and Net Zero, appointing former Business Secretary Grant Shapps to head the ministry.

He also launched a new Department for Science, Innovation and Technology, switching ex-Culture Secretary Michelle Donelan into that role.

Lawmaker Lucy Frazer was promoted to replace her as Secretary of State for Culture, Media and Sport.

Meanwhile Kemi Badenoch, seen as a rising star of the Tory party, expanded her brief as International Trade Secretary to include also heading the business ministry.

She also remains minister for women and equalities.

Sunak's Downing Street office said the creation of the new departments would "ensure the whole of government is geared up to deliver for the British people".

A statement added the changes will mean "the right skills and teams" are focussed on Sunak's most pressing priorities, which include halving inflation this year.