A concrete and steel security fence slices through the harbourside streets, the deserted squares telling the story of Australia's most stringent security lockdown in its history as Sydney hosts a summit of Asia Pacific leaders.

"I came the wrong day," said Sanaz Mohandessy, standing near the barrier 50 metres (yards) from the famed venue with its shelled roof.

A 24-year-old Iranian working for an insurance company, she said she would have to return next week instead.

The sweeping security measures were put in place to protect leaders of the 21-member Asia Pacific Economic Cooperation (APEC) forum, notably US President George W. Bush and his counterparts from China and Russia.

But it also means disappointment for other visitors to Sydney.

The Opera House itself is sealed off, every inch of it inspected minutely, cordons and the security fence keeping intruders at bay on land while yellow buoys warn boats to stay outside the limits.

"It's a big disappointment not to be able to go up the steps or visit it," said Nicole-Helene Antoine, a French tourist.

"We knew Bush was coming, but we did not imagine they would clamp down like this."

"It's a bit shocking and exaggerated," said her husband Michel. "If (French president Nicolas) Sarkozy were coming I'm not sure they would have done all that stuff."

Milan Cizek, who coaches a Slovakian bodybuilding team, lamented a wasted journey to Sydney where he had planned a stopover on the way back from New Zealand.

"We flew thousands of kilometres for nothing," he complained. "They should stay at home instead and have a video-conference."

While authorities say the security is needed to prevent violence at protest rallies, mostly targeting Bush, many people in Sydney have criticised them as disproportionate.

People like Thomas Davey, marketing manager of the Sydney Aquarium.

"The government has scared off international and inter-state visitors to Sydney with lots of negative pre-publicity," he told AFP. "Plus they have told local residents to take a holiday and leave the city."

Many people in fact have decided to take time off.

Friday, when most of the leaders arrived, has been declared a public holiday but the tourist office in the heart of the business district hasn't waited — it shut earlier this week.

The Museum of Sydney, constructed on the site of the first British colonial governor's house and normally open seven days a week, plans to shut for the entire weekend.

It has left bars, restaurants and other businesses which rely on tourists bereft of customers. Many have simply closed altogether or are shutting down early at night.

Daniel Stowell, of Yellow Water Taxis, said daily pick-ups had plummeted by up to 75 percent with cruises around Harbour Bridge facing stiff restrictions on speed and movement.

"People get discouraged by all the security. They get intimidated," he said beside his boat. "We're going to shut down for four days."

It's a similar story at the Opera Bar, where the terrace is empty despite the sunshine. "There's a huge drop," said Kit O'Shea behind the bar. "Normally we're full at this time of day."

Still, it's not all bad news. For Huang Zixi and Gao Sisi, cabin attendants working for Korean Air, fewer people means more space to enjoy.

"Compared to China, it is cleaner with much fewer cars and people," smiled Gao (23).

AFP