A supporter attends a "Britain Stronger in Europe" rally at Birmingham University in Birmingham, Britain June 22, 2016. REUTERS/Andrew Yates

LONDON (Reuters) - The campaign to keep Britain in the European Union got a boost from two opinion polls published late on Wednesday, a few hours before voters begin to cast their votes in a historic EU membership referendum.

The news pushed sterling to its highest level against the U.S. dollar so far this year on the signs of a last-minute rise in support for staying in the EU. Investors have mostly feared that a so-called Brexit would damage the economy in Britain and possibly beyond.

A telephone survey by polling firm ComRes, conducted for the Daily Mail newspaper and ITV television showed the “Remain” campaign had a 48 percent to 42 percent lead over “Leave”.

A previous ComRes poll for The Sun newspaper, which was published on June 14, had given a lead of just one point to the “Remain” camp which has been led by Prime Minister David Cameron and the heads of Britain’s other major political parties.

“As anticipated, the final campaign week has seen a boost for the status quo. But if ‘Remain’ win, as now appears likely, it will be a victory lacking enthusiasm,” Andrew Hawkins, chairman of ComRes, said in a statement.

At almost the same time, another poll by YouGov for The Times newspaper showed “In” leading “Out” by 51 to 49 percent. A previous YouGov poll for The Times had put “Out” ahead.

“Our current polling suggests the race is too close to call, but the recent trend has been towards ‘Remain’, just as other referendums in the past have shown late movement towards the status quo,” YouGov director Anthony Wells said.

Betting odds moved further in favour of a vote to stay in the EU after the two polls were published. Betfair, a gambling firm, showed the probability of an “In” vote rising to almost 80 percent.

Two other opinion polls published earlier on Tuesday both showed the “Leave” campaign narrowly ahead although one of them, by research firm TNS, showed its lead had been reduced to two points from seven points in its previous poll.