Leave the European Union campaigners wave banners near Parliament in London, Britain June 15, 2016. REUTERS/Stefan Wermuth

LONDON (Reuters) - The percentage of Britons who would vote to leave the European Union in next week’s referendum has risen seven points since last month to 45 percent, according to a telephone poll by Survation published on Thursday.

The poll, for spread betting provider IG, found 42 percent would vote to remain, down from 44 percent on May 25, while 13 percent were undecided.

When undecided voters were excluded, 52 percent backed leave, compared to 48 percent for remain, Survation said.

IG said its EU Referendum Barometer, an indicator of what traders are predicting will happen in next Thursday’s vote, showed a 58 percent chance Britain will vote to remain.

The chance of leaving has risen to an all-time high of 42 percent, it said, up from 25 percent at the start of the week after a string of opinion polls have put “Out” in the lead.

“Doubling down on fear in terms of campaign strategy isn’t working ... the Remain campaign needs to stop doubling down on fear and start talking about some hope and optimism for the future within the EU,” Damian Lyons Lowe, founder and Chief Executive of Survation, told IG.

“To the Leave campaign you’d say: ‘keep doing what you are doing because it’s working.’”

According to an Ipsos MORI phone poll earlier on Thursday, 53 percent of Britons would vote to leave, compared to 47 percent who want to remain in the bloc.

Survation interviewed 1,104 adults by telephone on Wednesday.