BANGKOK, Jan. 22 (Xinhua) -- Prime Minister Abhisit Vejjajiva Thursday ordered police to make more efforts to investigate into the murder case of four Saudi diplomats.

    "If the case remain unsolved, it will affect the country's image regarding justice," said Premier, according to Bangkok Post Website.

    The murder case has strained diplomatic relations between the two countries and Thai laborers have been banned from working in Saudi Arabia.

    The statute of limitations of this case will expire next year.

    Saudi diplomat Abdullah Al-Maliki was gunned down in Bangkok in1989. Diplomats Adbullah A Al-Besri, Fahad A Z Albahli and Ahmed AAlsaif were assassinated in January 1990. The deaths were purportedly linked to the theft of priceless jewelry from a Saudi prince, according to Asia-Pacific News.

    Several past Thai governments have attempted in vain to upgrade relations with Saudi Arabia.