Australia should seriously limit the intelligence it shares with Britain if Jeremy Corbyn becomes prime minister, our longest-serving foreign minister warns.
Britain goes to the polls on December 12 as conservative Prime Minister Boris Johnson attempts to win a mandate for his Brexit plans.
Alexander Downer, who was also Canberra's man in London over the past five years, says while most British Labour MPs hold centre-left views, the party's leadership was "very, very far left".
"It would change the whole nature of our engagement with the UK if Jeremy Corbyn became the prime minister," he told the National Press Club in Canberra on Tuesday.
The British Labour leader and those around him were "unsympathetic and hostile to Western interests" on foreign policy, Mr Downer said.
Britain is Australia's second most important security partner within the Five Eyes grouping and our intelligence agencies have an intimate and important relationship.
"Under a Corbyn government, they will abandon that support for the Western alliance and steer a completely different foreign policy and security policy direction to such an extent that I think we would be unwise to continue the intelligence-sharing relationship with a Corbyn-led Britain of the kind that we have today," Mr Downer said.
"We would substantially wind it back.
"We would have to be very careful what sort of intelligence we shared with a government like that."
He also warned a Corbyn government and its radical, Venezuela-style agenda would lead to the "very substantial deterioration" of Britain's economy.
"That would put at risk the investments that we have as a country, particularly our superannuation funds, made in the UK," Mr Downer said.
He estimated there was a 70 per cent chance Mr Johnson and the conservatives would retain power, but said if they didn't win their own right, Mr Corbyn would likely be prime minister.
The Howard-era foreign minister also cautioned that if Britain does leave the European Union as planned, the EU would over time likely become less interested in Australia, despite a trade deal now being negotiated.
"The bureaucrats in Brussels see Australia as a bit player," he said.
"For us as Australians, the European Union will be more difficult to deal with in the years ahead than it has been while Britain has been there."
Australian Associated Press