UN Secretary General Kofi Annan has turned down - for now - a request by Lebanon to extend an inquiry into the death of its former prime minister.
A blast in Beirut killed Hariri and 20 others
Mr Annan said he wanted to see a report on Rafik Hariri's assassination, due on Friday, before granting an extension.
Lebanon formally asked last week that a UN team investigating the killing be given more time.
Mr Hariri was killed in February in a massive bomb blast in Beirut that also killed 20 other people.
Mr Annan said on Monday he wanted to deal with the investigation on a purely "technical" basis, and he was determined "not to allow a politicisation of the process".
Syria, the main power in Lebanon until its military withdrawal earlier this year, has been blamed by many Lebanese for the assassination, but denies any involvement.
However UN investigator Detlev Mehlis has listed four pro-Syrian Lebanese generals as suspects, and questioned seven Syrian officials, including Interior Minister Ghazi Kanaan, who was found dead last week after apparently committing suicide.
Mr Annan told reporters at the United Nations that there had been "no serious discussion" of widening the probe to investigate Mr Kanaan's suicide.
French police announced on Monday they had arrested Zuhair Mohammed al-Siddiq, a former Syrian intelligence officer accused of lying to the UN investigation, in Paris.
In another development, Lebanese Prime Minister Fuad Saniora called for diplomatic relations with Syria and the demarcation of their common border, despite Syria's long-time insistence that the countries were so close they did not need diplomatic relations.