A Turkish cargo ship has collided with a Greek warship off the Aegean Sea island of Lesbos, fuelling fears of a “hot incident” in what has long been a traditional theatre of tension between the Nato rivals.

The vessel rammed into the Greek gunboat, Armatalos, early on Friday within hours of Alexis Tsipras, the Greek prime minister, giving a keynote speech on the island.

“After the incident, the cargo ship increased speed and made off to Turkey’s nearest coast without responding to the radio messages of the Armartalos,” the Hellenic Navy said.

A Navy statement described the pre-dawn collision as occurring in Greek national waters in flagrant violation of international law. “There were no injuries,” it said. Turkey’s transport ministry also announced that there was no threat of “casualties or environmental pollution”.

But while damage to the warship – part of a Nato-led operation monitoring illegal migration flows in the Aegean – was also described as minimal, the incident highlighted the friction between the countries.

Tensions have been running unusually high in recent months. This week Nikos Kotzias, Greece’s foreign minister, said Ankara had “come close” to “crossing a red line” when a Turkish patrol boat rammed a Greek coastguard ship off a disputed Aegean isle in February. The two neighbours nearly went to war over the uninhabited islet in 1996.

“If there hadn’t been a calm and composed approach on the Greek side, no one can say where this could have led,” Kotzias told Skai TV.

Senior figures in Greece’s military and naval command have expressed nervousness that the scene is being set for a clash ahead of crucial presidential elections in Turkey next month. The Islamic-leaning Justice and Development party (AKP) has joined forces with the Nationalist Movement party (MHP) to contend the election at the request of Recep Tayyip Erdoğan, the president. The nationalists are virulently at odds with Greece over Cyprus, and other territorial disputes, and have laid claim to numerous inhabited isles in the Aegean.

“We are tracking a lot of Greek nervousness and worry among the military,” said one western diplomat. “There is genuine concern over the rise in what are regarded as provocative violations.”

With air violations and mock dogfights also increasing dramatically, it is vital that channels of communication remain open if the danger of miscalculation and miscommunication is to be kept at bay, military observers say.

“And, sadly, at the moment we are not seeing a lot of that,” the diplomat added.

Last month, Turkish warplanes flew dangerously close to a military transport helicopter carrying the Greek prime minister over the Aegean.

In a separate incident, Greek troops fired warning shots at a Turkish helicopter as it flew over an outlying Aegean island. Turkish fighter jets in defiance of a gentleman’s agreement to respect religious holidays, had only hours before entered Greek airspace on Orthodox Easter Sunday.

The infraction occurred over a military outpost visited earlier in the day by Panos Kammenos, the defence minister.

Analysts downplayed the the idea that Friday’s collision was deliberate but did not rule it out completely.

“It appears to be an accident, such accidents have happened before,” said Ioannis Michaletos at the Institute for Security and Defence analysis. “But as there have been so many incidents of late it could also have been staged. Relations between the two countries are tense and the naval theatre is one where clashes occur.”

Analysts and diplomats agreed that, so far, EU member Greece had reacted coolly in a clear bid not to be drawn into combat.

“Greece has more to lose,” said Michaletos. “In the event of a hot incident, tourism would lose greatly and that could mean the final collapse of the economy.”