UNITED NATIONS, April 12 (Xinhua) -- UN Secretary-General Ban Ki-moon said on Thursday he was very concerned about the lack of progress in the establishment of a special tribunal to try suspects in the murder of former Lebanese prime minister Rafik Hariri.

    "I am very much concerned by the lack of progress in this issue," Ban told reporters at the UN headquarters. "Again, I hope the Lebanese government will take the necessary constitutional procedures."

    Ban said he had received letters from many parliamentarians from Lebanon and had spoken by telephone on Wednesday with Prime Minister Fuad Siniora.

    Last week, Ban received a letter from 70 Lebanese lawmakers asking him to act under the UN Charter to set up a special tribunal given the continuing deadlock in the Lebanese Parliament.

    The secretary-general said he was still studying the letters and request from the Lebanese government.

    "While I am studying all these letters and telephone calls, even at this time I hope the Lebanese government will take the necessary measures, constitutionally, among themselves, through dialogue, by promoting national reconciliation," he said.

    The United Nations and the Lebanese government have signed an agreement on the creation of the special tribunal which still needs approval from the country's parliament.

    Hariri was killed with 22 others in a suicide truck bombing in Beirut in February 2005.