Image caption The referendum will take place on 5 May next year.

The proposed wording for the question in the referendum on changing the UK voting system needs to change, the Electoral Commission says.

Some people - "particularly those with lower levels of education or literacy, found the question hard work and did not understand it" - its report says.

The watchdog says the structure, length and the language used made the question "harder to read than it needed to be".

Deputy Prime Minister Nick Clegg promised to assess the recommendations.

The final wording of the question is a matter for the UK Parliament.

WHAT IS ALTERNATIVE VOTE? Instead of marking the ballot paper with an X for one candidate, the voter can rank all the candidates in order of preference.

If a candidate receives a majority of first-preference votes then they are elected.

If no candidate gains a majority of first preferences, then the second-preference votes of the candidate who finished last on the first count are redistributed.

This process is repeated until someone gets over 50%

Representatives are still elected for single-member constituencies

The question proposed by the government is: Do you want the United Kingdom to adopt the 'alternative vote' system instead of the current 'first past the post' system for electing Members of Parliament to the House of Commons?

The Electoral Commission's suggested redraft is: At present, the UK uses the 'first past the post' system to elect MPs to the House of Commons. Should the 'alternative vote' system be used instead?

The referendum, part of the coalition agreement between the Conservatives and Lib Dems, is due to take place on 5 May next year.

Under the alternative vote (AV) system, voters rank candidates in their constituency in order of preference.

Anyone getting more than 50% of first-preference votes is elected. If no-one gets 50% of votes the candidate with the fewest votes is eliminated and their backers' second choices allocated to those remaining. This process continues until one candidate has at least 50% of all votes cast.

The Liberal Democrats back a change to AV, but the Conservatives oppose it, and the two coalition parties have agreed that each will campaign for their own preferred system in the run-up to the referendum.

'Slight change'

New Labour leader Ed Miliband says he will be backing a change to AV in the referendum.

Jenny Watson, Electoral Commission chairwoman, said: "People told us that the wording of the question - with some changes - was easy to understand. However, they have a limited knowledge of what the 'first past the post' system is and almost no understanding of the 'alternative vote' system.

"Our research took place without the campaigns and extensive media coverage that will be in place in the run-up to the referendum. We found that when participants had more information on how both systems worked, their understanding improved and they could cast their vote in the way they intended.

"Campaign groups and the media will play an important role in the run-up to the referendum. And the Electoral Commission will also be playing its part, by providing every household in the UK with information on both voting systems and how they can cast their vote."

Mr Clegg, who is overseeing the government's constitutional reform programme, said: "They have suggested in their report a slight change to the question we proposed and we will look at it. It's only just come out.

"It's quite right that the Electoral Commission should have tested the question. That's why we provided them with our own thoughts on the question and we will look at their recommendations."