LONDON (Reuters) - The once double-digit lead of the campaign to keep Britain in the European Union over the rival "Out" camp has narrowed to just one percentage point, according to an opinion poll published by The Sun newspaper on Tuesday.

Just over a week before Britons vote in a June 23 EU referendum, the telephone survey of 1,002 people found support for staying in the bloc stood at 46 percent compared with 45 percent in favor of leaving, The Sun said.

A previous ComRes telephone poll, published on May 19 for the Daily Mail newspaper and ITV television, gave the "In" camp a lead of 11 points.

"There has evidently been a significant move in the last few weeks," Tom Mludzinski, ComRes' Director of Political Polling, was quoted as saying in The Sun.

"We had seen 'Remain' holding a comfortable lead, but after the debates and the agenda switching to immigration, it has narrowed the gap with 'Leave' now in touching distance," he said.

A separate, online poll published earlier on Tuesday by polling firm TNS gave a seven-point lead to Leave, following similar signals from other recent surveys, which have pushed down the value of sterling and wiped billions of pounds off the stock market.

The ComRes poll showed 9 percent of respondents said they did not know how to vote. Excluding the "don't knows," the "In" campaign led "Out" by 51 to 49 percent, The Sun said.

(Writing by William Schomberg; editing by Chris Reese, G Crosse)