LONDON (REUTERS) - The campaign for Britain to leave the European Union has a two-point lead over the rival "In" camp, down from a seven-point lead last week, according to a TNS poll published on Wednesday, the day before the country's EU membership referendum.

TNS, a market research firm, said 43 per cent of respondents would vote to leave, while 41 per cent would vote to remain and 16 per cent were undecided or did not intend to vote.

The poll was conducted online and interviewed 2,320 adults between June 16 and 22.

"It should be noted that in the Scottish Independence Referendum and the 1995 Quebec Independence Referendum there was a late swing to the status quo and it is possible that the same will happen here," Luke Taylor, head of social and political attitudes at TNS UK said in a statement.

"Clearly, with a race as close as this, the turnout level among different demographic groups will be critical in determining the result."

A TNS poll published on June 14 found 47 percent of likely voters would opt to leave the EU ahead of 40 per cent who wanted to stay.

Earlier on Wednesday, a poll by another research firm, Opinium, gave the "Out" camp a one-point leave over "In," causing sterling to fall against the dollar and the euro .