Turkey has said it will suspend all financial dealings with Syria and freeze the assets of Bashar al-Assad's government as part of sanctions against its former ally.
Announcing the measures apparently aimed at persuading the Syrian president to end his crackdown against anti-government protesters, Ahmet Davutoglu, the Turkish foreign minister, said in Ankara on Wednesday that Assad's government had come "to the end of the road".
He said Turkey will block the delivery of all weapons and military equipment to Syria.
"Every bullet fired, every bombed mosque has eliminated the legitimacy of the Syrian leadership and has widened the gap between us," Davutoglu said.
"Syria has squandered the last chance that it was given."
Davutoglu said Syria "has entered a vicious circle of violence", despite warnings from Turkey.
"Syria must immediately cease using force on the people and the forces must immediately withdraw from the cities,
He also said a co-operation agreement with Syria was being suspended until there was a new government in place.
"Until a legitimate government which is at peace with its people is in charge in Syria, the mechanism of the High Level of Strategic Co-operation has been suspended," Davutoglu said.
The Turkish steps follow in the wake of sanctions announced by the Arab League, which have been described by Walid al-Muallem, Syria's foreign minister, as equivalent to "economic warfare" and thus giving Syria the right to use its strategic location to inflict economic damage of its own.
"[Those 912 prisoners freed did] not have Syrian blood on their hands"
- Syrian state news agency
Al Jazeera's Hashem Ahelbarra, reporting from the Turkish-Syrian border, said the decision to impose sanctions was a "significant step for the Turkish government", as it demonstrated that it has "completely lost faith in the leadership in Damascus.
"The sanctions will put more pressure on Syria," he said, adding that previously Turkey and Syria had strong trade relations, and had many plans to work together.
Ankara has said any sanctions would not hurt the Syrian people and has ruled out cutting off electricity and water supplies. It has also said civil aviation by Turkish Airlines to Damascus will continue.
Meanwhile, Syria released 912 prisoners detained for involvement in protests against Assad on Wednesday, the state news agency said.
Those freed did "not have Syrian blood on their hands", the agency said. It said Wednesday's move followed the release earlier this month of more than 1,700 prisoners.
'Ready for any scenario'
Davutoglu had said on Tuesday that Turkey was ready for any scenario if Syria continues its crackdown on protests against Assad, but that his country is opposed to a military option against its neighbour.
In an interview with television broadcaster Kanal 24, he said: "We hope that a military intervention will never be necessary.
In-depth coverage of escalating violence across Syria
"However, the Syrian regime has to find a way of making peace with its own people to eliminate this option. If the oppression continues, Turkey is ready for any scenario."
Davutoglu also said the international community may decide a buffer zone is needed in Syria if increasing numbers of people try to flee the violence there.
"If tens, hundreds of thousands of people start advancing towards the Iraq, Lebanon, Turkey borders, not only Turkey but the international community may be required to take some steps such as a buffer zone," he said.
"We don't want that to happen but we must consider and work on that scenario."
Turkey has stepped up its criticism of the government's crackdown on Syria's uprising after Turkish diplomatic missions came under attack by pro-government demonstrators in several cities earlier this month.
Davutoglu's sanctions announcement came a day after Sergey Lavrov, the Russian foreign minister, dismissed calls for an arms embargo on Syria and cautioned against imposing ultimatums on Assad's government.
Speaking in the Russian capital, Moscow, on Tuesday after a meeting with the Icelandic foreign minister, Lavrov said that calls for an arms embargo on Syria were "unfair".
He said that armed groups opposing the Syrian government had been supplied from the outside.
He drew parallels to the fighting in Libya, where he said the West armed the opposition forces despite a UN arms embargo.
Lavrov said Syria's problems could not be solved by ultimatums and reaffirmed Moscow's call for a political settlement.
A Russian defence ministry official told the ITAR-TASS news agency that his country’s only aircraft carrier and its most modern anti-submarine destroyer will lead a powerful flotilla on a rare port call to Syria before the end of the year.
The flotilla will reach the little-used Russian base in the port of Tartous by New Year's Eve on a mission that was planned in advance and has no direct relation to Syria's intensifying standoff with the West, the official said.