WATCH: Police in hot pursuit of wallaby across Sydney Harbour Bridge

Swamp wallabies, which are smaller marsupials than their kangaroo cousins, are rarely seen in cities

A wayward wallaby disrupted traffic by hopping across the Sydney Harbour Bridge on Tuesday with police in pursuit.

The adult male was captured without any apparent serious injury and is expected to be released back into the wild within days.

Swamp wallabies, which are smaller marsupials than their kangaroo cousins, are common across eastern Australia, but are rarely seen in cities.

The startled wallaby hopped across the bridge's eight lanes of traffic an hour before sunrise then turned onto an motorway on the harbour's southern shore towards the Sydney Opera House.

A pursuing police car with flashing lights videoed the animal's steady bounding before police officers captured him near the Sydney Conservatorium of Music and wrangled him into a horse float, police said.

Veterinarian Larry Vogelnest said the wallaby was "quite distressed" but he gave it a tranquilizer before taking it to the wildlife hospital at nearby Taronga Zoo.

The wandering wallaby is being cared for by the Taronga Zoo. EPA

"It had some minor grazes on its face and its hind legs," Mr Vogelnest said. "There don't seem to be any major injuries."

Mr Vogelnest said he did not know where the wallaby had come from or how it found its way to the bridge.

"It's unusual obviously to have a wallaby running around on the Harbor Bridge, but there are more and more of these wallabies turning up in bush land close to the city." he said.

Police Inspector Kylie Smith said several police cars plus horse-handlers from the police mounted unit had responded to the wallaby alert.

"When police arrived, the wallaby refused to obey police directions and initially evaded police," Ms Smith said.

Six officers eventually caught it, including the horse-handlers who attempted to calm it down, she said.

"It was a very unusual job for a city police officer to be chasing a wallabydown the Harbour Bridge," she said.

The wallaby was lucky it did not attempt the journey an hour later at 6am local time when traffic would have been far heavier, Ms Smith said.

A motorist who identified himself as Ray told a Sydney radio station of his surprise at seeing police cars with flashing lights pursuing a wallaby.

"I'm from the bush, I'm used to seeing them running all over the place, but I've never seen one so close in the city before," he said.