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 at least 10 people were killed 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.
National Coalition 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 conditions attached.
Khatib, speaking to reporters in Cairo, proposed that direct talks with regime representatives could take place in "liberated areas" of rebel-dominated northern Syria.
Just across the border from northern Syria, at least 10 people were killed and dozens wounded when a car exploded just inside Turkey, Turkish officials said, although the cause was not immediately clear.
A Syrian-registered car is believed to have been at the centre of the blast in a buffer zone at the frontier, a foreign ministry official told AFP, adding that the likelihood of it being a terrorist attack was "51 percent".
The official said the dead included four Turks and six Syrians.
He said the blast barely 40 metres (yards) into the buffer zone from the Cilvegozu crossing triggered a fire that damaged around 15 humanitarian aid vehicles. "There are up to 50 wounded people, so the number of dead could go up."
Another Turkish 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.
The explosion comes after a suicide bomber attacked the US embassy in Ankara on February 1, killing a Turkish security guard and wounding three others. That attack was claimed by a radical Turkish Marxist group.
Monday's blast also came less than three weeks after NATO declared that a battery of US-made Patriot missiles had become operational on Turkey's border with Syria.
Turkey, a one-time Syria ally which is now vehemently opposed to Assad's regime, has taken in almost 200,000 refugees from the conflict and serves as a transit point for rebel fighters.
-- Largest dam seized --
On the ground, rebels on Monday 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, 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.
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.
Rebels in the northern city of Tabqa burned down a massive statue of late president Hafez al-Assad, Bashar's father and predecessor, according to amateur video distributed by the Observatory.
The Observatory, which relies on a vast network of activists on the ground and medics, said at least 66 people, including 27 civilians, were killed in violence across Syria on Monday.