Britain is to be investigated for possible human rights breaches, over concerns about postal vote fraud.
Postal votes have proved controversial
Two Council of Europe officials will visit London in December, to assess whether it is necessary to officially monitor the UK's voting procedures.
Tory MP David Wilshire, who pushed for the resolution, said the government had failed to put its "house in order" to prevent fraudulent voting.
Minister Bridget Prentice said "robust measures" had been put in place.
The visit follows a resolution, signed by 18 members of the Council's Parliamentary Assembly, citing "a growing body of evidence that widespread absent vote fraud is taking place in the United Kingdom".
That has been backed by the Assembly's monitoring committee, which has appointed a former German justice minister and a Polish senator to look into allegations of irregularities in Birmingham, Blackburn, Coventry and London.
If they find that official monitoring is necessary - Britain will join ten of the 46 Council members which are already monitored, including Albania, Russia, Serbia and Ukraine.
Since the UK introduced postal and proxy voting on demand in 2001, there has been a series of allegations of vote rigging.
A judge looking into vote rigging in Birmingham's 2004 local elections said he had heard evidence of fraud that "would disgrace a banana republic".
The Electoral Commission has pressed for a system where each voter registers individually, rather than by household, to reduce fraud.
This was resisted by the government in its Electoral Administration Act, which fears it would lead to a drop in people registering to vote.
Mr Wilshire, a member of the British delegation to the council, accused the government of "systematically ignoring" pleas from the Electoral Commission.
"If the British government won't put its own house in order, you mustn't be surprised if there are some of us who will try to find someone else who will make them put their house in order," told BBC Radio 4's World at One programme.
But constitutional affairs minister Bridget Prentice told the BBC postal vote fraud was rare.
"In the last two years we have put in very robust systems to deal with fraud and other issues within our electoral system," she said.
Some aspects of individual registration have been put in place for the next elections - people will have to write in and ask for a postal vote, sign for it and give their date of birth.
"That's a very secure system in ensuring that the person who does apply for the vote is the genuine voter," she said.
Sam Younger, chairman of the Electoral Commission, said once the Act was fully implemented, it should remove the opportunity for fraud "considerably" - although the watchdog would still like to see individual voter registration.
But he added: "We're perfectly happy to talk to whoever wants to come and look at our system and investigate it."
The Council of Europe upholds the Human Rights Convention, which requires member states to "hold free elections ... which will ensure the free expression of the opinion of the people in the choice of the legislature".