Poland’s prime minister has said an explosion on a railway line leading to the Ukraine border this weekend was caused by “an unprecedented act of sabotage”, and vowed to catch those responsible “regardless of who their backers are”.

Visiting the scene this morning, Donald Tusk said the damage done to the railway tracks on Sunday was deliberate and likely aimed at blowing up the train. He expressed relief there were no casualties.

Speaking later in Warsaw, after an emergency meeting of security officials, Poland’s special services minister said there was a “very high chance” that the blast was carried out on the orders of “foreign services”.

He didn’t name Russia directly but Poland has experienced a series of major arson and sabotage attacks in recent years, including parcel bombings, that it sees as part of Moscow’s hybrid war on the West.

Poland’s railway network is a critical part of the military supply lines for neighbouring Ukraine as well as a route for civilians moving in and out of the country.

Investigators are looking into a second incident that occurred further down the same line on Sunday, where a packed train was forced to stop suddenly. It’s thought “very likely” to be another case of sabotage – though not an explosion.

“These events show that the people behind it have decided to begin a new phase of threatening the railway infrastructure,” Special Services Minister Tomasz Siemoniak said.

Russia always denies any role in such attacks.

The damage near Mika, about 100km (60 miles) south-east of Warsaw, was detected at around 07:30 local time (06:30 GMT) on Sunday morning by a train driver who was forced to make an emergency stop.

Photographs from the scene appear to show a section of track missing. There were only two passengers and several staff on board the train and no one was hurt.

On Monday the interior minister confirmed that the use of explosives was “beyond any doubt”, though he didn’t go into detail, citing the ongoing investigation.

A local resident told Polish TV he had heard a blast the previous evening.

“It shook the whole building, the windows… it all trembled so much,” the man said, adding that people several kilometres away had felt the impact.

He thought at first it was a gas explosion, or a falling drone. A police patrol investigated but found nothing untoward.

The following morning, several trains passed over the damaged section of track and one reported the problem back to base but the line was not closed.

No suspects have yet been detained but officials say police have collected a significant amount of evidence, including footage from nearby security cameras, to help identify who carried out this “shameful act of sabotage”.

The strong language and close focus on the incident come as Poland investigates another suspected hybrid attack involving parcel bombs sent from Lithuania last year using a courier service.

One exploded just outside Warsaw and a second was intercepted. Another reached the UK on a cargo plane and went off in a DHL warehouse.

A number of suspects are in custody in Poland awaiting trial, including a Russian man, said to be one of the organisers, who was extradited from Bosnia.

There have been multiple other cases using people recruited via the Telegram messenger app, using accounts that Poland believes are run by Russian intelligence.

Two years ago, more than a dozen people were found guilty of installing secret cameras close to the railway lines in Poland that are used to send weapons and equipment to Ukraine.

But this is the first direct attack on the network.

Some experts quoted by Polish media suggest the aim was mainly psychological: that the explosives were meant to derail the train, not destroy it, to scare Poland off continuing its support for Ukraine.

But the Justice Minister said anyone involved would be found and prosecuted “ruthlessly” and there was “no place on earth they can hide”.

Despite the symbolic show of strength – with several security officials and a prosecutor lined up on stage in suits – government ministers faced a barrage of questions about how such sabotage was possible and why the damage to the track wasn’t located sooner.

In a tetchy exchange, the officials insisted that the response had been swift and effective and that it was “untrue and insulting” to criticise.