President Bashar al-Assad vowed on Monday not to bow to mounting pressure and "plots", almost two years into a deadly revolt in Syria, as nine people died when a car exploded just inside the Turkish border.
On the warfront, rebels seized control of Syria's largest dam, a monitoring group said.
"Syria will remain the beating heart of the Arab world and will not give up its principles despite the intensifying pressure and diversifying plots not only targeting Syria, but all Arabs," Assad said, quoted by state news agency SANA.
Opposition chief Ahmed Moaz al-Khatib, meanwhile, said he had received "no clear response" from Damascus over his offer of dialogue.
Khatib said in late January he was prepared to hold direct talks with regime representatives without "blood on their hands," on condition the talks focus on replacing Assad.
The Assad regime has said it was open to talks but without pre-conditions.
Khatib proposed that direct talks with regime representatives could take place in "liberated areas" of rebel-dominated northern Syria.
"The issue is now in the regime's camp. It has given no clear response yet that it accepts that (Assad) will leave. There has been no official contact until now," Khatib told reporters in Cairo.
Just across the border from northern Syria, nine people were killed and dozens wounded when a car exploded inside Turkey, Turkish officials said, although the cause was not immediately clear.
A Syrian-registered car was believed to have been at the centre of the blast on Turkish soil, local mayor Huseyin Sanverdi told Turkey's NTV news channel.
An official from the Turkish foreign ministry confirmed the deadly explosion, adding that the blast triggered a fire that damaged around 15 humanitarian aid vehicles.
The explosion struck barely 40 metres (yards) from the Cilvegozu crossing, NTV said, adding it might have been caused by a mortar bomb fired from the Syrian side.
But another foreign ministry official said a suicide bomber might have been involved in the blast that smashed apart the gates at the crossing, opposite Syria's Bab al-Hawa post.
Turkey, a one-time Syria ally which is now vehemently opposed to Assad's regime, has taken in almost 200,000 of refugees from the conflict.
On the ground, rebels seized control of the largest dam in Syria, a vital barrier along the Euphrates River in the northern province of Raqa that generates 880 megawatts of power, the Syrian Observatory for Human Rights said.
"This is the biggest economic loss for the regime since the start of the revolution," which the United Nations says has cost more than 60,000 lives since it broke out in mid-March 2011, Observatory head Rami Abdel Rahman told AFP.
Rebels from the jihadist Al-Nusra Front and the Awayis al-Qurani and Ahrar al-Tabqa battalions met little resistance in the area, as loyalist security chiefs fled on board military helicopters from a nearby airbase, he said.
The capture of the dam is the latest in a string of key rebel victories in northern and eastern Syria but the insurgents have yet to take a major city in the war-ravaged country.
-- 'We will leave no stone unturned' --
Elsewhere, warplanes bombarded two districts of southern Damascus, Assali and Qadam, said the Observatory, while rebel fighters seized control of a bridge linking insurgent-held suburb Irbin to Jobar district in the east of the capital.
Fighting also raged in the Ashrafiyeh district of the embattled northern city of Aleppo for a fourth consecutive day, pitting rebels against pro-regime militia and Kurdish fighters.
Rebels in the northern city of Tabqa on Monday burned down a massive statue of late president Hafez al-Assad, Bashar's father and predecessor who ruled the country with an iron fist for 30 years, according to amateur video distributed by the Observatory.
"Here is my message to the oppressors of the country: 'We will come for you, and we will leave no stone unturned till we find you,'" said a little girl at the scene, waving a black flag and wearing a pink headscarf.