Syria escalated tensions with Turkey on Monday, accusing its neighbor and former friend of imperialist delusions reminiscent of Ottoman dynastic rule, as Syrian Army gunners exchanged artillery blasts with their Turkish counterparts across the border for the sixth consecutive day.
Insurgent sympathizers and the Syrian government described an extremely violent day in the nearly 19-month-old uprising in Syria. In unverified accounts, killings and destruction were reported in the cities of Aleppo, Homs and Dara'a and in northern Idlib Province, where members of the rebel Free Syrian Army claimed to have discovered a massacre committed by security forces at a makeshift prison.
In Damascus, there were reports that a suicide attacker had detonated a bomb near a government intelligence compound.
The new violence coincided with word that the Syrian National Council, the main opposition group in exile, which has been plagued by leadership dysfunction and factionalism, was trying to make itself more relevant to a future political solution by convening a special conference next week in Doha, Qatar.
In what appeared to be part of that effort, the council's president, Abdulbaset Sieda, was said by the news organization Al Arabiya to have visited Bab al-Hawa, a rebel-held border town, on Monday. If true, the trip would be his first into Syria since he became the group's leader in June.
Mr. Sieda was quoted in a telephone interview with The Associated Press as saying the group would not rule out a future role for any members of President Bashar al-Assad's government, as long as they had not ordered killings or participated in them. By some estimates more than 20,000 Syrians have died.
Mr. Sieda seemed to be trying to revive suggestions floated in the council that some of Mr. Assad's subordinates could have a soft landing in a post-Assad government. Those suggestions had gained little support as others in the council, which has rarely spoken with a unified voice, insisted that everyone in Mr. Assad's government was irrevocably tainted.
As a possible interim leader, Mr. Sieda mentioned a Syrian vice president, Farouk al-Sharaa, whose name had also been floated in an Arab League peace plan that went nowhere.
George Sabra, a spokesman for the council, played down the significance of Mr. Sieda's statement, saying the council welcomed anyone who had not participated in killing. What constitutes participation, however, is unclear. Mr. Sharaa has been an important figure in Mr. Assad's hierarchy for years.
"The issue is not just names," Mr. Sabra said by telephone. "But we need a plan. What's the benefit if we change names and keep the regime? Do you think people will accept that?"
He also said that the council had "no problem" with Mr. Sharaa, but that "no one can decide, or approve, except the Syrian people."
Mr. Sharaa's name as an interim president also was broached over the weekend by the Turkish government, which has long hosted members of the Syrian National Council. The Turkish foreign minister, Ahmet Davutoglu, said Mr. Sharaa's hands "are not contaminated in blood."
But that idea was dismissed on Monday by Syria's information minister, Omran al-Zoubi, in a reaction reported by the official Syrian Arab News Agency. Mr. Zoubi accused the Turkish government of behaving as if the world had reverted to the Ottoman dominance that shaped the Middle East for centuries.
"Turkey isn't the Ottoman Sultanate," Mr. Zoubi said. "The Turkish Foreign Ministry doesn't name custodians in Damascus, Mecca, Cairo and Jerusalem."
He said the Turkish foreign minister's statements reflected "obvious political and diplomatic confusion and blundering," according to SANA.
Mr. Zoubi's rejoinder came as Turkey shelled Syrian targets across the border on Monday after a Syrian shell hit the Altinozu district of Hatay Province, where farmers were working. The semiofficial Anatolian News Agency said there were no injuries.
Turkey and Syria once enjoyed one of the strongest friendships among Middle Eastern neighbors. They became estranged after Mr. Assad's government brutally suppressed the political opposition that started with peaceful demonstrations in March 2011.
Turkish and Syrian border troops have been shelling each other since Wednesday, after a Syrian mortar shell killed five civilians in Turkey, a NATO member. The shelling has raised fears that the unrest in Syria will broaden into a regional war.
Syria has accused Saudi Arabia and Qatar of joining with Turkey in arming the insurgents, an accusation that gained some credibility with a report on Monday by BBC News, which said its correspondent had seen three crates of what appeared to be Saudi weapons diverted to a rebel base in Aleppo.
Reporting was contributed by Anne Barnard, Hwaida Saad, Hala Droubi and Hania Mourtada from Beirut, Lebanon, and Sebnem Arsu from Istanbul.
This article originally appeared in The New York Times.