Prosecutors have dropped charges against two Romanian teenagers who were accused of raping a schoolgirl in Ballymena, an allegation that triggered race riots in Northern Ireland.

The Public Prosecution Service (PPS) on Friday cited “significant evidential developments” in its decision to end criminal proceedings against the boys, aged 14 and 15.

They had been charged with raping the teenage girl on 7 June in the County Antrim town, an allegation that sparked a violent campaign against foreigners, especially ethnic Roma immigrants from eastern Europe. Dozens of families fled and copycat disturbances spread to other towns. A third teenager suspected of involvement in the alleged attack reportedly fled to Romania.

The PPS said in a statement it had a duty to consider new information or evidence that became available. “We have recently been made aware of significant evidential developments in this case. In light of this new evidence, it has been determined that the test for prosecution is no longer met on evidential grounds, and therefore the case should not proceed.”

Prosecutors and the police investigation team met the complainant and her family earlier on Friday to explain the decision, the PPS said.

Belfast youth court granted the request to withdraw charges, paving the way for the release of the boys from the juvenile detention centre where they have been held since June. Because of their age they have not been named. “This is a very sensitive case, but the matters are now marked withdrawn. The less I say about it the better,” the district judge, George Conner, told the court.

DCI Stephanie Finlay said any reported sexual crime was investigated and urged victims to come forward. “You will be dealt with sensitively and will be offered the appropriate additional support.”

Finlay appealed to the public to not speculate about the Ballymena case. “I would remind everyone to remain respectful in light of today’s decision, and refrain from speculation, particularly on social media,” she said.

The collapse of the prosecution gave a fresh twist to a case that became a focus for anti-immigrant protests.

Ballymena, a largely Protestant town about 25 miles (40km) north of Belfast, is 95% white, according to the 2021 census. However, an influx of people from eastern Europe, many of whom worked at food processing plants, prompted complaints from some residents.

Accounts of the alleged rape last June spread swiftly on social media – in court it was claimed that the girl was dragged down an alley and attacked by three boys in a garage in the Clonavon Terrace area.

Hundreds of people, many wearing masks or in hoods, targeted foreign-owned homes and businesses in a three-night spree of smashing, burning and missile-throwing that terrorised immigrants from the Philippines, Bulgaria, the Czech Republic, Romania and other countries. “Where are the foreigners?” some shouted.

Some rioters attempted to focus attacks on ethnic Roma people, prompting people to put signs with statements such as “Filipino lives here” on their homes. Others erected union flags and loyalist bunting in the hope of deflecting attacks. Mobs assaulted police, leaving dozens injured, and disturbances spread to Larne and Portadown.

There are no official figures but one informed source with ties to the Roma community in Ballymena estimated that two-thirds of the approximate pre-riot population of 1,200 had left.