Now back to their home in Grodno, Belarus, activist Andrzej Pisalnik and his wife Iness Todryk-Pisalnik were taken to Minsk earlier on Wednesday to testify as witnesses in a lawsuit against the board of the Union of Poles in Belarus.
The activists themselves told the Polish Press Agency that their flat was not shaken down. Nevertheless, the Pisalniks were barred from using their telephones throughout the day.
Both of the activists were brought before the Investigative Committee in Minsk where they were interrogated.
Poland's Foreign Ministry has been monitoring the situation and confirmed prior to the release of the activists, who are also members of the Union of Poles in Belarus (ZPB), that they had been taken to Minsk.
Several high-ranking members of the Union of Poles in Belarus (ZPB) have been arrested in recent weeks, including the organisation's president, Andzelika Borys, who was charged with "inciting hatred" and "rehabilitating Nazism" along with other ZPB officials. They face up to 12 years in prison.
Ms Borys, along with other ZPB officials, has been charged with "inciting hatred" and "rehabilitating Nazism" and could face 12 years in prison.
The arrests have fuelled fears that the Belarusian authorities have launched a persecution campaign against the country’s Polish minority.
On Wednesday morning, Andrzej Pisalnik told Polish Radio that the police had started searching his apartment in Grodno, near the Polish border. Contact with Mr Pisalnik and his wife was then lost and the Belarusian Association of Journalists reported that the couple had been detained and taken from Grodno to Minsk.
The Polish Ministry of Foreign Affairs confirmed the information to PAP, stating that on April 13, Mr Pisalnik had been questioned by the Grodno Prosecutor's Office and that the police had entered his apartment on April 14.
"The Polish diplomatic-consular service and also the highest authorities of the Republic of Poland have undertaken from the start all possible activities aimed at securing the rights of the Polish national minority in Belarus, and especially their representatives who have become the victims of harassment," the ministry said.
The foreign ministry gave its assurance that Polish consular officials in Belarus remain in constant contact with the families of detained people.
"The consular assistance foreseen in international law is, however, hampered due to the fact that those arrested have Belarusian citizenship," the Polish foreign ministry added.
In a communique cited by Belarusian state news agency BielTA on Wednesday, the prosecutor's office said Andrzej Pisalnik had broken the law by telling the media that an "anti-Polish campaign" is taking place in Belarus and that he had received an "official warning about the inadmissibility of repeated violations of the law."
According to the prosecutor, Mr Pisalnik's statement was an attempt at "inciting national and linguistic hatred, arousing aversion and distrust towards the Belarusian authorities and spreading false information about their activities."
Mr Pisalnik and his wife are ZPB activists and work for the Znadniemna.pl website. They have recently reported on the criminal cases brought against the ZPB's leadership and inspections conducted by the authorities at schools and organisations of the Polish minority in Belarus.