(Updates with results of Tuesday's poll, Ipsos MORI expected on Thursday)
LONDON, June 7 (Reuters) - Britain holds a national election on Thursday. Opinion polls have shown that Prime Minister Theresa May's lead over the opposition Labour party has ebbed over the last three weeks, with some even putting her majority in doubt.
Below are the results of recent polls, and details of opinion polls expected before Thursday's vote.
* A Survation poll showed late on Monday that the lead of May's Conservative Party over Labour stood at just one point.
* The poll was conducted on Friday and Saturday, before an attack in London by Islamist militants that killed seven people and injured 48.
* An Opinium poll on Tuesday showed that May was set to boost her majority, finding that the Conservatives had widened their lead over Labour to 7 points.
* The new poll was the first by a major firm that was conducted in its entirety after the deadly attack in London by Islamist militants on June 3. The field work ran from June 4-6.
* Likely to be published on Wednesday afternoon London time, but has sometimes appeared earlier.
* A Panelbase poll on Thursday last week showed May's lead almost halved to eight points, compared with 15 points a week earlier.
* Likely to be published on Wednesday evening.
* A Kantar poll last Wednesday showed May's Conservatives had extended their lead to 10 points over Labour, up from eight in the previous week
* Likely to be published on Wednesday evening, London time.
* ComRes polls are among those showing the biggest lead for Theresa May. The latest poll, published on Saturday, showed she had a 12-point advantage over Labour, unchanged from a week earlier.
* Likely to run late afternoon or early evening, London time on Wednesday.
* Like ComRes, the ICM polls have shown sizeable leads for the Conservatives, albeit narrowing sharply from record levels around a month ago.
* The latest ICM/Guardian poll published on Monday showed May's lead slipped to 11 points, down one point from the previous week.
* YouGov is expected to publish its final poll in The Times on Wednesday evening. A YouGov poll for the Sunday Times published on June 3 gave the Conservatives a four-point lead. Its last poll for The Times published on May 31 showed gave them a three-point lead.
* A model-based projection from YouGov on Monday showed May was on track to win 305 seats in Britain's parliament, 21 seats short of a 326-seat majority. That projection is updated on a daily basis.
* Ipsos MORI polls for the Evening Standard newspaper have tended to run shortly after 11:00 a.m. London time (1000 GMT/0600 ET).
* The last Ipsos MORI published on June 2 showed the Conservatives' lead contracted to five points, compared with 15 points two weeks previously. (Reporting by William Schomberg; Writing by Andy Bruce and Alistair Smout; Editing by Hugh Lawson)