Japan's Shinzo Abe is the latest name to join the lengthy list of world leaders warning against a "leave" vote at the EU referendum. The prime minister said the UK would become "less attractive" to Japanese investors after a Brexit because businesses saw Britain as a "gateway" to the continent.

"Japan very clearly would prefer Britain to remain within the EU," Reuters news agency reported Abe saying. "Many Japanese companies set up their operations in the UK precisely because the UK is a gateway to the EU." The Japanese leader added: "Britain's friends around the world, including Japan, will be watching your decision on 23 June with very close attention."

The comments came during a joint press conference with British Prime Minister David Cameron at Number 10. The intervention follows Barack Obama's own Brexit warning, which saw the US president claim the UK would be at the "back of the queue" for a trade deal with the US if it voted to break away from Brussels.

"Maybe some point down the line there might be a UK/US trade agreement, but it's not going to happen any time soon because our focus is on negotiating with a big bloc, the EU, to get a trade agreement," Obama said.

President Barack Obama makes emotional pro-EU plea to British voters during UK visit IBTimes UK

Narendra Modi, the prime minister of India, Chinese President Xi Jinping, and Australia's foreign minister Julie Bishop have also warned the UK electorate against a Brexit from the 28-nation-bloc. But despite the heavyweight interventions, the EU referendum opinion polls are neck-and-neck.

The latest online survey from BMG, of more than 1,500 people between 22 and 26 April, put "leave" on 45% (unchanged) and "remain" on 43% (+2). Matthew Elliott, the chief executive of Vote Leave, accused Abe of adopting a "do as I say, not as we do" attitude.

"Japan wouldn't accept the huge loss of control Britain has suffered because of our EU membership, so much of the public will be sceptical of the Japanese prime minister's 'do as I say, not as we do' attitude," the Brexit campaign chief said.

"Japanese bosses argued that we would be diminished if we didn't join the euro so similar warnings about the referendum further lack credibility. The EU has a terrible record negotiating trade deals yet we've handed power over our trade to Brussels and that's on top of the £350m ($507m) we pay the Commission every week."

This is what you really need to know about the Brexit vote IBTimes UK