WASHINGTON - US GOVERNMENT investigators say they are looking closely at a track circuit near where a deadly transit train crash occurred in Washington.

Debbie Hersman of the National Transportation Safety Board says five of six circuits, or stretches of track, in the area showed no problems during tests on Wednesday. But she says there were anomalies with the sixth circuit. Ms Hersman would not elaborate on what those might be, saying more tests are needed.

Equipment along each circuit receives signals that generate speed commands for the train. Ms Hersman said the circuit in question is about 225 metres long.

Nine people were killed on Monday when a train plowed into a train that was stopped. It was the deadliest accident in the 33-year history of the subway system known as Metro. -- AP