ATHENS (Reuters) -Three people were slightly injured on Tuesday in a fire inside Greece's second-biggest oil refinery west of Athens, the company said in a statement.

The fire broke out on Tuesday in refining units, forcing workers to evacuate as a column of black smoke poured across the evening sky.

Images in local media showed tall flames at the refinery, run by Greek company Motor Oil, about 70 km (44 miles) west of Athens. The refinery was evacuated.

"The situation (in the refinery) has improved," the company said in the statement, adding that the cause of the fire was not yet known.

It said that the three people who suffered light injuries have been taken to hospital. They all worked for a contractor company.

Fire crews sent three helicopters and 11 fire engines to the scene, the fire brigade said. A general message was sent to residents to evacuate the area.

Local authorities closed a highway near the refinery and the rail company said trains had been halted.

(Reporting by Lefteris Papadimas and Angeliki Koutantou; Writing by Edward McAllister; Editing by Mark Potter and Sandra Maler)