ATHENS, Dec. 12 (Xinhuanet) -- A powerful explosion rocked central Athens early Monday morning, causing damage in an area near the finance ministry and a central post office, a ministry spokesman said.

    Greece's national Television ERT reported that the explosion occurred at 6:10 a.m. near the post office and the ministry at Syndagma Square. A fire broke out immediately.

    Two persons were lightly injured by broken glass, police said. The explosion scattered debris over a wide area, damaging the facade of the post office and blowing out windows along nearby streets. TV footage showed damaged cars, cafes and shops nearby.

    It was not immediately clear who was behind the blast. Police said a warning phone call by an unidentified man was made beforehand to Eleftherotypia, a local Greek-language daily, announcing that an explosion would occur near the Ministry of Economy and Finance.

    A police source said a bomb appeared to have been planted on the back of a motorcycle that was abandoned between the ministry and the post office.

    The blast coincided with the beginning of a week of heavy strike action in Greece, over changes to public sector contracts.

    Greece's largest union has called for transport strikes on Monday and again on Thursday, and a 24-hour strike has been planned for Wednesday across the public sector. Enditem