BEIRUT -- Turkey fired artillery into Syria for a fourth consecutive day on Saturday after another Syrian mortar shell landed on the Turkish side of the increasingly tense border.
The exchanges -- and Turkey's recent warnings to Syria that it would defend itself -- have raised fears of regional conflict. While stray shells and bullets from the Syrian conflict have often landed in Lebanon and Turkey, for the first time a Syrian shell killed five Turkish civilians on Wednesday, prompting Turkey's response.
Both Syria and Turkey on Saturday denied that Syria had pulled its forces back 6 miles from the border to avoid provoking Turkey, as Turkish news media had reported on Friday. A Turkish government official dismissed the reports as unreliable.
Rebel activity was heightened along the border area in Syria's Idlib province on Saturday. Anti-government activists said rebels had seized the Syrian village of Khirbet al-Jouz, not far from where the mortar shell landed in a field in the Turkish village of Guvecci; another Turkish official confirmed in an interview that rebels had taken control in the area. Also, rebels claimed to have seized a checkpoint at Darkush, also in the border region.
Potential spillover from the Syrian conflict is a concern not only in Turkey but on all of Syria's borders. Some Lebanese officials believe Syria wants to drag Lebanon into the conflict to reduce international focus on Syria and raise the stakes if the Syrian president, Bashar Assad, falls.
On Saturday, unnamed Lebanese officials told the local news media that a prominent media adviser to Mr. Assad had been involved in a plot uncovered this summer to stir sectarian violence in Lebanon, suggesting that the Syrian government was more deeply involved than previously alleged. A Lebanese security official, speaking on the condition of anonymity, later made the same charges in an interview.
Lebanon had already charged Michel Samaha, a pro-Syrian politician in the plot, which it said would have loosed a campaign of bombings and assassinations inside Lebanon.
The Syrian government adviser said to be involved, Bouthaina Shaaban, had presented a cosmopolitan face for the government during Mr. Assad's early years in office, when the president was portraying himself as a reformer. It was impossible to immediately confirm the accusations, and Syria made no statements on the matter.
The Lebanese official said that evidence from tapped phone calls suggested that Mr. Shaaban had worked with Mr. Samaha, who was accused of transporting explosives to Lebanon and plotting explosions aimed at "big crowds" and Sunni politicians who support the Syrian uprising. "From the phone records we have, we managed to track a call between Samaha and Bouthaina Shaaban," the official said. "Both were talking explicitly and clearly about the operation."
The allegations about Mr. Shaaban were first reported by Lebanon's MTV channel.
In another province bordering Turkey, Latakia, unusually intense fighting was reported. Latakia, the home province of the Assad family's Alawite clan, had previously remained relatively calm. Activists said 10 rebels were killed trying to seize a military outpost.
Continued heavy shelling was reported on Saturday morning by anti-government activists in the city and province of Homs. Shelling was also reported near Damascus and in the southern province of Daraa. The government has struggled to maintain control in those areas, even after repeatedly shelling them and declaring order restored.