May 5 (Reuters) - Ahead of Britain's parliamentary election on Thursday, Prime Minister David Cameron's Conservatives and the opposition Labour Party are tied at 34 percent, according to a YouGov opinion poll for the Sun newspaper published on Tuesday.
The poll showed Conservatives and Labour both up one percentage point from Monday, polling company YouGov said.
The election is expected to be the tightest in decades.
The two main parties have been neck and neck in most opinion polls since the start of the year, with neither establishing a sustained lead exceeding the three-point margin of error.
Opinion polls have consistently shown that neither of the two main parties is likely to win an overall majority in the 650-seat Parliament. (Reporting by Aurindom Mukherjee in Bengaluru; Editing by Steve Orlofsky)