Turnout is up by around 9% on average

Turnout so far stands at 40% overall, up 9% on last year's figures.

In the four regions piloting all-postal ballots, the number of people casting their votes rose by 13%, compared to the 7% hike in other areas.

The boost comes in the wake of concerns about voter apathy after the decline in turnout in recent elections.

With several councils not starting their counts until Friday morning, there are no firm conclusions about the general increase in turnout.

Among possible explanations are the fact that the local elections this year took place on the same days as the European polls.

Protest motives?

Some commentators have suggested some voters who have stayed at home in recent years may have gone back to the polls this year to register a protest vote over the Iraq war.

Labour has faced criticism for pushing ahead with the all-postal voting trials in four regions of England: the North West, North East, East Midlands and Yorkshire and the Humber.

But election experts say there is no evidence that the introduction of all postal voting has helped the Labour Party.

Labour's share of the vote has declined by exactly the same amount in areas with all-postal ballots as in those areas using conventional voting methods.