Syria has issued arrest warrants for 33 Lebanese and international officials for allegedly misleading the UN-backed investigation into the assassination of Lebanon's former PM Rafik Hariri.
Those named include a German prosecutor and Lebanese police chief Ashraf Rifi.
The move is seen in Beirut as a Syrian attempt to put pressure on Lebanon to abandon the tribunal which is expected to indict some Hezbollah members.
Syrian-backed Hezbollah has vowed to retaliate if its members are indicted.
In a startling about-turn, current Lebanese Prime Minister Saad Hariri said last month that the accusations levelled by him and his allies that Syria was involved in the murder of his father were "political" and had been withdrawn.
But that was not enough to defuse the tensions with Syria and its allies, especially Hezbollah, says BBC Middle East correspondent Jim Muir.
Both deny any involvement in the killing and say the UN investigation has been politicised.
Syria made the decision to issue the arrest warrants on Sunday in the case of Major General Jamil Sayyed, the former head of Lebanon's General Security Department, his lawyer said.
Gen Sayyed was one of four pro-Syrian officers arrested in 2005 on suspicion of involvement in Mr Hariri's assassination and released in 2009 because of a lack of evidence.
In December 2009, he filed a lawsuit in Damascus against various defendants who he alleges were involved in a conspiracy of false testimonies intended to point to the involvement of Syria and its supporters in Mr Hariri's killing.
He turned to the Syrian courts after his repeated efforts to bring cases in Lebanon against so-called "false witnesses" in the Hariri investigation had come to nothing.
His lawyer, Fasih al-Ashi, said that the Syrian judge issued the arrest warrants after repeated state summons went ignored.
Lebanese police chief Ashraf Rifi, one of the 33 people named in Gen Sayyed's case, dismissed the move.
"We will work to prevent the implementation of these warrants, which violate... Lebanese sovereignty," he told Reuters news agency.
But Syria's ambassador to Lebanon, Ali Abdel Karim Ali, said the warrants were not politically motivated or aimed at harming relations between the two countries.
"This is a purely legal case," he said. "The issue is not linked to bilateral relations between Prime Minister Saad Hariri and Syria... I think Hariri is aware of that and our relations with him continue."
Last month, Mr Hariri said he had been wrong to accuse Syria of assassinating his father, adding that the international inquiry had been misled by false testimony.
So far, an understanding between Mr Hariri's Saudi allies and Syria have managed to keep the lid on civil peace in Lebanon, says our correspondent.
While the arrest warrants are unlikely to be implemented in practice, many of those named are close political allies or associates of Mr Hariri himself, he adds.
Rafik Hariri died in a massive truck bomb attack in Beirut in 2005. Syria has always denied involvement in his death.
Syria dominated Lebanon for nearly 30 years and kept tens of thousands of troops on its soil.
Hariri's death sparked anti-Syrian protests that led to Syria's withdrawal.