The Russian government is looking into an allegation that one of its jets operating in Syria violated Turkish airspace for a second time, the Russian embassy in Ankara said on Tuesday, according to the TASS news agency.
Turkey complained late on Monday that a Russian warplane had violated its airspace on Sunday, the second such breach in three days, prompting Ankara to once again summon Moscow's ambassador.
The first such incursion, on Saturday, prompted the United States and NATO to denounce Russia, and Ankara to threaten to respond, raising the prospect of direct confrontation between the former Cold War adversaries.
"The Turkish Foreign Ministry summoned our ambassador for the second time on Monday," Igor Mityakov, the Russian embassy's press attache, was quoted as saying. "The Turkish side handed over information linked to a violation of its airspace. The Russian side is checking the data," he said.
The Russian Defense Ministry said the first incursion had been accidental and that a Su-30 jet had entered Turkish airspace "for a few seconds." It said "necessary measures" had been taken to ensure there would be no repeat of the incident.
Moscow said the Syrian airbase from which Russian planes were flying missions, Khmeimim, was located about 30 kilometers (18.64 miles) from the Turkish border and that its aircraft had to approach it from the north in certain weather conditions.
"The incident was the result of unfavorable weather conditions in the area," the ministry said in a statement on Monday, referring to the first incursion. "So there's no need to look for any conspiracy theories here."
Russia has denied another Turkish assertion that one of its planes locked its radar onto two Turkish fighter jets.
NATO's Secretary-General said on Tuesday he doubted Russia's explanation that its weekend violations of Turkey's airspace were a mistake because there were two such incursions and they lasted longer than just a few seconds.
"I will not speculate on the motives but this does not look like an accident … and we have two of them," Jens Stoltenberg told a news conference, referring to the incursions and noting their duration.
Stoltenberg said the U.S.-led NATO alliance, of which Turkey is a member, had not received "any real explanation" of what happened. He said he had not had any direct contact with Moscow but NATO has discussed the possibility of using its military lines of communication with Russia.