A British vote to leave the European Union would be "irreversible" and the country could only rejoin the bloc on what would be unacceptable terms, Foreign Secretary Philip Hammond warned Monday.
"The message we are trying to get across to the British people is that this is an irreversible decision -- if they decide to leave, there will be no going back," Hammond said as he arrived for a meeting with his EU counterparts in Luxembourg .
"Britain could never rejoin the EU at a later date except on terms that would be unacceptable -- membership of the euro, membership of (the) Schengen (passport-free zone) and so on," he said.
The most recent opinion polls show voters once more swinging behind the remain camp after a strong showing by Brexit supporters in the previous two weeks.
Hammond said "the referendum battle ... is close fought. It will be a very tight result either way."