Turkey claims Syria also shot at one of its search and rescue planes, as diplomats prepare for Nato meeting

Turkey has sharply raised the stakes in a military standoff with Syria, claiming one of its search and rescue planes was shot at as it tried to find a Turkish jet shot down on Friday by Syrian gunners.

Bülent Arınç, the deputy prime minister, said the rescue plane had been attacked as it flew over the Mediterranean searching for two pilots. The claim undermines Damascus's insistence that the first jet was attacked due to mistaken identity.

Nato is to hold consultations in Brussels on Tuesday morning over the incident, but the meeting will not lead to any form of military response, according to diplomats.

The downing of the Turkish military plane over what Ankara says were international waters was denounced by European Union foreign ministers. They called for full Syrian co-operation with an investigation and imposed a new round of sanctions on Bashar al-Assad's regime.

"The EU condemns the unacceptable shooting down by Syria of a Turkish military plane on 22 June. It offers its sympathies to the families of the airmen involved and commends Turkey's measured and responsible initial reaction," they said.

Turkey has called a meeting on Tuesday of the National Atlantic Council, Nato's political steering body made up of ambassadors from member states, under article four of the North Atlantic treaty, which allows any member to consult its allies whenever it believes "the territorial integrity, political independence or security of any of the parties is threatened".

Turkey had said on Monday that it would push Nato to consider Syria's downing of the jet as an attack on the whole military alliance.

Despite deep frustration among many Nato countries over the conflict in Syria – where the opposition says Assad's crackdown on an increasingly armed popular uprising has killed 14,000 people – it is unlikely the military alliance will take armed action.

Arınç said Turkey retained its right to retaliate against what he called a hostile act, but said: "We have no intention of going at war with anyone."

He added: "We will of course use all rights granted under international law … until the end [which] also includes retaliation many-fold. This includes all sanctions that can be applied to the aggressor state under international law."

Syria tried to defuse tensions with its northern neighbour, claiming the Turkish air force F-4 Phantom had been flying at low altitude on a route previously been used by Israeli warplanes.

A Syrian foreign ministry spokesman, Jihad Makdissi, said the Turkish jet had been hit by anti-aircraft gun and was in Syrian airspace. Turkish officials claimed it had been struck by a more sophisticated anti-aircraft missile and that the Syrian military had not issued a warning.

Ankara acknowledged that the jet had flown over Syria for a short time, but said such temporary overflights were common and had not led to an attack before.

Tensions remain high on the Turkish-Syrian border, where 33 loyalist officers and soldiers, among them a brigadier general, crossed out of Syria with their families on Sunday night.

Defections from the regime's forces to the Free Syria Army have been constant for the past few months, but Damascus maintains control of many key divisions and is not known to have lost any members of its most elite units or inner sanctum.

Defecting officers are received with formality at Turkish military bases near the border and given more freedom to move around the country than fleeing soldiers, most of whom are taken to nearby refugee camps.

Sinan Ulgen, a former Turkish diplomat now at the Carnegie Endowment for International Peace, said: "The downing of a plane by one of Turkey's neighbours is unprecedented. Turkey is going to Nato and the UN security council to appease Turkey domestic opinion.

"On the bilateral level, it has no tools left. All the Syrian diplomats have been expelled and Turkey has no representation in Damascus any more. Its only option is to seek support from Turkey's partners in the multilateral arena.

"Statements of solidarity from western capitals will help Turkey fulfil two objectives: they will assuage domestic public opinion and Turkey can also use the incident as proof that the situation vis-a-vis Syria will remain volatile and unsustainable as long as Assad is there."

Meanwhile, a Russian ship carrying attack helicopters that was last week prevented from sailing to Syria has now been refitted with a Russian flag, rousing suspicions it is being prepared for a second attempt.

The MV Alaed, carrying air defence systems and helicopters, was forced to return to port after its British insurers withdrew cover as the ship rounded Scotland.

The Foreign Office and Treasury had warned the insurance company, Standard Club, that they could be in breach of sanctions against the Assad regime if they allowed the ship to pass.

Speaking in the House of Commons on Monday, David Cameron welcomed an insurance ban on all EU ships carrying arms to Syria. The prime minister said the EU ban was the result of UK actions.

The MV Alaed, sailing under the Curacao flag, returned to Murmansk on Sunday. Owner Femco said it was "awaiting further instructions".

Last week, Sergei Lavrov, Russia's foreign minister, admitted the Alaed was carrying supplies for Syria. "The ship was carrying air defence systems, which can be used only for repelling foreign aggression and not against peaceful demonstrators, and it was carrying three repaired helicopters," Lavrov told Ekho Moskvy radio.

Russia has repeatedly brushed off criticism of its continuing support for Assad, insisting it was merely fulfilling long agreed contracts in delivering supplies to Syria.

An unidentified "military-diplomatic source" told the Interfax news agency on Sunday that the Alaed would soon travel from Murmansk to Syria in a second attempt to deliver the shipment.

"The ship will travel under escort to avoid any sort of provocation," the source said. The escort ship would not be a navy ship, the source added.

Meanwhile, Femco said the ship's final destination was the far eastern port of Vladivostok and it would sail under the Russian flag "in order to protect its interests, the security of the ship and the protection of its crew, all of whom are citizens of Russia". Analysts say the flag change could cause an international incident if any attempts are made to board it. Local reports said the Russian flag was raised over the ship on Monday.

"We don't plan on justifying ourselves, because we haven't violated anything – not international law, not a UN security council resolution, not our own national laws on export controls, which are some of the strictest in the world," Lavrov said last week.

Syria is Russia's main remaining ally in the Middle East, a key weapons client and host to its base at Tartus, Russia's only military base outside the former Soviet Union.