Tourists and locals hoping to visit the three wildlife parks in Mandai - the Singapore Zoo, Night Safari and River Safari - can now get there by hopping on a coach from the city.

The new service, called Safari Gate, was officially launched on Tuesday and is a collaboration between tour company Duck & Hippo and Wildlife Reserves Singapore, which owns the parks.

The coaches depart hourly from two locations, Suntec City and the Singapore Flyer, starting from 8.30am. They make 20 trips a day to the parks and back, with the last returning coach at 10.30pm. Each ride takes between 45 minutes and an hour.

One-way tickets cost $7 for an adult and $5 for a child, and do not include park admission charges.

The service allows visitors to tour the parks at their own time and pace, said Duck & Hippo's chief executive James Heng. "(It's) a departure from the current market offering of fixed-time group tours. It's free and easy, no more fixed timing or itinerary," he said.

Since the soft launch of Safari Gate a month ago, the number of people using the service to get to the three parks has doubled, Mr Heng added.

Chief executive of WRS, Mr Lee Meng Tat, said: "During peak periods or when it's raining, it's difficult for visitors to get a taxi to Mandai. We want to offer them as many alternative transport options as possible."

As part of the launch, a group of guests from the Movement for the Intellectually Disabled of Singapore (Minds) were brought to the River Safari onboard one of the coaches to spend an afternoon there.