Britain's economy contracted slightly more than thought in the third quarter, revised official data showed on Thursday.

Gross domestic product shrank 0.3 per cent in the July-September period compared with an original reading of minus 0.2 per cent, the Office for National Statistics said in a statement.

The ONS added that the UK economy grew weaker than expected in the first half of 2022.

It comes after the UK government said it believes the economy is already in recession on fallout from sky-high inflation.

Darren Morgan, director of economic statistics at the ONS, said the "revised figures show the economy performed slightly less well over the last year than we previously estimated, with manufacturing and electricity generation notably weaker".

It comes as Britain experiences severe strike action by workers across public and private sectors, as wage increases fail to keep pace with the country's annual inflation rate of nearly 11 per cent.