Ministers have been accused of not consulting the devolved administrations about the proposed date of a referendum on the Westminster voting system.
The 5 May 2011 date, the same day as national elections in Wales, Scotland and Northern Ireland, has led to claims simultaneous polls will confuse voters.
Labour said the date had been "foisted on" the country for political reasons.
But Cabinet Office minister Mark Harper said there had been proper discussion and MPs backed the proposal in a vote.
He told MPs that responsibility for the administration of devolved elections ultimately lay with the UK government and ministers would do all they could to ensure the "smooth running" of the elections.
MPs are currently debating legislation required to pave the way for a referendum on the way they are elected and whether to change the current first-past-the-post system in favour of an Alternative Vote method.
During the committee stage of the bill on Monday, the coalition won a vote on the proposed 5 May date by 335 votes to 207.
The referendum pledge was a key part of coalition agreement between the Conservatives and the Liberal Democrats but the proposed 5 May date has angered opposition MPs in Scotland, Wales and Northern Ireland, who believe it will detract from national elections there.
Tory MPs are also concerned about the arrangement, fearing it could distort turnout in the referendum as there will be no other elections in some areas of England and residents will have less incentive to take part.
Mr Bryant, shadow justice minister, said there had been an "extraordinary" lack of consultation with devolved assemblies about the proposed poll date and its impact on devolved elections.
There was a "firm view" among these assemblies that the date was a bad idea and it showed a lack of respect to Scotland, Wales and Northern Ireland, he suggested.
"It would just seem to be common human decency to be able to consult," he told MPs, adding this "betrayed the rather London-centric view of the government".
Although most Tory MPs are opposed to electoral reform and more than 40 have signed a motion calling for the 5 May date to be changed, they will ultimately be expected to support the bill.
For the government, constitutional reform minister Mark Harper said responsibility for elections in Scotland, Wales and Northern Ireland was still a reserved matter.
He noted that there had been no "formal" motion in any of the devolved Parliaments criticising the 5 May date.
But he insisted there had been discussions between senior government ministers and the first ministers of the respective nations about the implications of the poll date and with the leaders of political parties in the devolved nations.
"They have been raised," he said. "Clearly the devolved administrations may still disagree - and probably still - with the decision the Westminster government has taken but these issues have been discussed."
He rejected claims that voters would be confused by a multiplicity of polls, saying this had happened in the US for many years and the British public were "perfectly capable" of differentiating between the separate votes.
"What we have added is one extra vote which has a simple yes or no. It is not a complex election system."
Concerns were also raised about the scope for confusion over postal voting procedures.
Mr Harper said anyone who registered for a postal ballot for general elections would be entitled to one for the referendum but several MPs said people in that position - yet who had not requested a postal ballot for local elections - would simply not take part in the latter poll.
Counting of votes in the devolved nations would take priority over the referendum, the minister added, and counting in the AV poll and the announcement of the result would probably not take place until 9 May.