An Australian barbecue event has caused a fiery spat between Singapore locals and the ruling party's grassroots supporter base.

Prime Minister Tony Abbott and his Singapore counterpart Lee Hsien Loong were photographed flipping steaks at one of the '50 BBQs' hosted by Singapore's Australian High Commission to celebrate 50 years of diplomatic relations between Singapore and Australia on Sunday.

But just hours before the first steak was set to sizzle, locals were outraged to learn that attendance would be restricted by a ticketing system controlled by the People's Association, the grassroots supporters of the ruling People's Action Party.

'50 BBQs' was billed as an open, public event where Singaporeans would be treated to an Aussie-style BBQ where 10,000 beef and lamb steaks would be served at 23 sites across the island.