By William James
HANGZHOU, China (Reuters) - British Prime Minister Theresa May rejected a "points-based" system to screen immigrants, setting up a potential conflict with Brexit campaigners in her government who promised to bring in Australian-style controls over EU migrants.
May, who favoured staying in the European Union but has promised to deliver on the June 23 referendum vote by steering Britain out of the bloc, said such systems were difficult to manage and there was no "silver bullet" on immigration.
May has made clear that there will have to be tougher controls over immigration but has yet to say how the rules will work - a crucial issue for employers and for negotiations with the EU over future British access to the European market.
"There is no single silver bullet that is the answer in terms of dealing with immigration," she told reporters on her way to a G20 summit in China, citing her experience as Britain's longest-serving interior minister in over 50 years.
"One of the issues is whether or not points-based systems do work," May said.
A spokeswoman for May later told reporters that Britain would control immigration but that a points-based system "will not work and is not an option." The spokeswoman said the way controls would work had yet to be determined.
Australia vets immigrants according to their occupation, qualifications and other factors. A source close to May's thinking said she objects to points-based systems because they are hard for the government to control and she would prefer something that can be more directly influenced.
The comments offer the first glimpse into May's stance on the hardest question thrown up by the referendum: how to tighten border controls with the EU without losing access to its single market.
Britain's 27 partners are so far adamant that it cannot enjoy full trade benefits unless it continues to let in EU nationals as before.
In a sign of the extent of international concern over the impact of Brexit, Japan published a 15-page report setting out dozens of its requests of Britain and the EU including maintaining access to workers from the EU and UK.
The prime minister risks upsetting key members of the team she assembled in July to deliver an EU exit that protects Britain's global standing and carves out a new role for the country at the vanguard of global free trade.
Foreign minister Boris Johnson and trade minister Liam Fox were part of the 'Brexit' camp that argued that voting to leave the European Union would free Britain from the duty to admit all EU nationals who want to live and work here, enabling it to cut immigration.
Speaking in June before he was appointed as foreign minister, Johnson - figurehead of the Leave campaign and May's one-time rival for the prime minister's job - said a points-based system could bring back democratic control and better meet businesses' needs.
May's words will fuel fears among voters and Eurosceptic lawmakers that having a pro-Remain prime minister in charge will result in a watered-down version of Brexit that does not represent what people voted for.
"I’m worried," Nigel Farage, one of the most prominent Brexit campaigners and former head of the UK Independence Party, told BBC radio when asked about May's comments.
Farage said British voters had endorsed the idea of a points based system of immigration that would ensure Britain took well- vetted EU immigrants.
British lawmakers will on Monday debate a public petition calling for a re-run of the EU referendum. While four million people signed the petition, May has said the referendum result was clear and that "Brexit means Brexit".
Asked whether immigration controls precluded access to the EU single market, May said she was optimistic about what sort of deal Britain could negotiate.
"I want to be ambitious with what we can achieve, I don't take anything for granted, I'm going out there to get the best possible deal."
(Writing by Guy Faulconbridge; Additional reporting by Sarah Young; Editing by Mark Trevelyan and Giles Elgood)