Uber ride-sharing service is reportedly looking at a possible expansion in Portland as recruitment ads for experienced drivers appear on Facebook.

Uber is a fast growing ride-sharing taxi service that connects passengers and drivers with a smartphone app. The San-Francisco based company operates in 140 cities worldwide and is looking into a possible expansion. Building on its interest of launching the service in smaller cities, Uber is likely to bring its controversial taxi service to Portland. The information comes after some newly published advertisements on Facebook welcomed drivers in the Portland area to join Uber, reports Portland Press Herald.

The recruitment ads come with links to application and background check forms, and it is believed Uber is testing the Portland market for expansion of its ride-sharing service in Maine. So far the company has received a positive response from cab drivers and people of the city, Kaitlin Durkosh, a spokeswoman for Uber, said in an email statement to Portland Press Herald.

"So far, we've received overwhelmingly positive support from residents and visitors in the city looking for transportation alternatives like Uber, and interest from potential driver partners looking for economic opportunities," Durkosh wrote. "We are excited about the potential opportunity to connect riders and drivers in Portland."

Uber allows users to book a ride using a smartphone app. The company acts as a broker between the passenger and the driver, and takes a cut in the fares. Passengers can use the app to monitor the location of the car as it reaches the pickup point. Tips are pre-booked and paid from within the app, as users are required to store their credit card credentials. The service offers different options including luxury, SUV and UberX and low-cost rides. Uber is available in both major and less populated cities. Its services run in New York, Boston and Providence, Rhode Island, as well as small cities like Chapel Hill, North Carolina, Fairfield, Connecticut, and Palm Springs, California.

Uber also offers fluctuating pricing options and "surge pricing," which mounts up the fares of the cabs when there is a high demand. The company, which was launched in 2009, has been incredibly successful. It set a high record with its new round of funding that puts the company's value at $17 billion, Bloomberg reported last month.

When asked about Uber's arrival in Portland, a city's cab driver Musa Khater remained optimistic.

"I'm not a cab company so it's good for me," Khater told the Press Herald. "I've got a life, bills to pay and a family to take care of, and if (Uber) comes here and adds something to the Maine people, it's good. But if not, it won't be so good."