LONDON (Reuters) - Many more Britons than previously thought are working in jobs offering very little security, according to a sharp upward revision to official data on zero-hours contracts on Thursday.
Such contracts have come in for growing criticism from trade unions and the opposition Labour Party because workers are not guaranteed a minimum amount of work or pay each month, but are often expected to be able to work at short notice.
The Office for National Statistics said on Thursday that it now estimates a record 250,000 Britons were employed under the contracts in the last three months of 2012, compared with an earlier estimate of 200,000.
Even this may be well below the true figure: earlier this month the government said 300,000 people could be employed on such contracts in the social care sector alone.
The ONS said a further jump in the number of people it reports are on these contracts was possible due to methodological changes to be introduced for when it publishes data for the last three months of 2012.
Previously many people who said they worked on a shift basis in ONS surveys were not then asked if these were also zero-hours contracts.
"There is potential for a step change in the data when this is introduced," the ONS said.
- For a full explanation of the methodological changes, see here
Reporting by David Milliken; Editing by Ruth Pitchford