Nato has rejected Moscow's explanation that its warplanes violated the air space of alliance member Turkey last weekend by mistake and said Russia was sending more ground troops to Syria and building up its naval presence.

Russian Foreign Ministry spokeswoman Maria Zakharova, who yesterday strongly rebuffed US criticism of Russian air strikes in Syria.

With Russia extending its air strikes to include the ancient city of Palmyra, Turkish President Tayyip Erdogan said he was losing patience with Russian violations of his country’s air space.

“An attack on Turkey means an attack on Nato,” Erdogan warned at a Brussels news conference.

Nato Secretary-General Jens Stoltenberg said the alliance had reports of a substantial Russian military build-up in Syria, including ground troops and ships in the eastern Mediterranean.

“I will not speculate on the motives... but this does not look like an accident and we have seen two of them,” Stoltenberg said of the air incursions over Turkey's border with Syria. He noted that they “lasted for a long time”.

The incidents, which Nato has described as “extremely dangerous” and “unacceptable”, underscore the risks of a further escalation of the Syrian civil war, as Russian and US warplanes fly combat missions over the same country for the first time since World War II. The Russian Defence Ministry had said that a tSU-30 warplane had entered Turkish air space along the border with Syria “for a few seconds” on Saturday, a mistake caused by bad weather. Nato says a plane also entered Turkish air space on Sunday. A US official said the incursions lasted more than a few seconds and described Moscow's assertion that the incursions were an accident as “far-fetched”.

I will not speculate on the motives... but this does not look like an accident

Stoltenberg said the US-led alliance had not received “any real explanation” from Russia about the incursions. Disagreement over the air space violations came after disputes over the exact aims of the Russian air campaign. Moscow says it is attacking Islamic State but the West accuses it of striking other rebel groups to prop up Syrian President Bashar al-Assad.

In a further incident, a MIG-29 fighter of unknown nationality and Syria-based missile systems “interfered” with eight Turkish F-16 jets patrolling along the Syrian border on Monday, the Turkish military said.

According to a statement, the MIG-29 locked its radar on to the Turkish patrol for four minutes 30 seconds. The same planes were also harassed by a Syria-based missile system for four minutes 15 seconds. Russia’s Nato envoy said the alliance was using the accidental incursion to distort the aims of Moscow’s air campaign in Syria.

“The impression is that the incident in Turkish air space was used to plug Nato as an organisation into the information campaign waged by the West to distort the aims of the operations carried out by the Russian air force in Syria,” Alexander Grushko told reporters in Brussels.