President Bashar al-Assad has pledged co-operation with a UN inquiry into the death of Rafik Hariri, because Syria is "innocent and truth is its interest".
Assad says Syria will be accused of not co-operating whatever it does
However, he lashed out at international pressure on Syria and said co-operation would cease if Syria "would be harmed".
He was speaking in a televised speech in Damascus, seen by many as his last chance to avoid a showdown with the UN.
The UN team wants to question six top Syrian officials as part of its inquiry into the murder of the Lebanese ex-PM.
"We will play their game," Mr Assad said, but he held out little hope that this would avert pressure on his regime.
"No matter what we do and how much we co-operate, the result after a month will be that Syria did not co-operate."
Thousands of young Syrians gathered around the venue, a hall at Damascus university - which Mr Assad had attended - cheering and waving flags as the speech proceeded.
Syria has repeatedly denied any involvement in the Hariri killing, and has set up its own inquiry headed by prosecutor Ghada Murad.
The Syrian inquiry has reportedly begun questioning six members of Mr Assad's inner circle - in effect preventing them from travelling to Beirut to give evidence as the UN has demanded.
On Wednesday Syrian official media said the chief UN investigator, Detlev Mehlis, had been invited to Damascus to discuss co-operating with Syria's investigation.
But Mr Assad said the German prosecutor had refused the government's offer to permit the questioning of the officials within Syria, including at UN offices there, or at the Arab League headquarters in Cairo.
The speech was followed with interest in neighbouring Lebanon
Mr Assad also criticised the Lebanese government as a puppet for Syria's enemies and its prime minister, Fouad Siniora, a "slave of all masters".
"The truth we see today is that Lebanon has become the platform, the factory and the financier of these conspiracies," he said.
Mr Siniora declined to comment on the speech to journalists in Beirut, but parliamentary supporters voiced shock.
"This is unbecoming of the president of Syria," said Druze leader Walid Jumblatt in an interview with Reuters news agency.
Last week, the UN Security Council adopted a resolution demanding Syria co-operate fully with the inquiry and detain suspects identified by Mr Mehlis.
Syria has until 15 December to comply or it will face further action, the resolution says.
Syria has criticised Mr Mehlis for making accusations without due process and not offering evidence.
The killing of Mr Hariri in a car bombing in Beirut in February led to widespread criticism of Syria, which was forced to withdraw its soldiers from Lebanon as a result.