Prosecutors believe the fire started when champagne bottles with sparklers attached were raised too close to the ceiling in the bar's basement level, igniting the sound insulation foam.
A former fire safety official in the Swiss ski resort of Crans-Montana remained silent when questioned by prosecutors on Wednesday investigating a deadly New Year bar fire, his lawyer said.
"My client exercised his right to remain silent as he does not yet have access to the case file," lawyer Fabien Mingard told the AFP news agency.
"He will answer the public prosecutors' questions as soon as he has access to the file."
The former head of the Crans-Montana municipality's fire safety department has not been named by Swiss media.
"The hearing lasted only 15-20 minutes because the defendant refused to cooperate after being informed of the charges," Robert Assael, one of the lawyers for the civil parties in the case, said.
"I am shocked that he did not answer the questions when the victims...are only waiting for one thing: the truth," he said.
The blaze at Le Constellation, a bar in the upmarket Alpine resort, broke out in the early hours of 1 January as people celebrated the New Year.
A total of 41 people, most of them teenagers, were killed and another 115 were injured in the disaster.
Nine people are under criminal investigation in the case.
They include the bar's French owners, husband and wife Jacques and Jessica Moretti, who face charges of manslaughter by negligence, bodily harm by negligence and arson by negligence.
They have twice been questioned at length by public prosecutors and lawyers for the civil parties.
Nicola Meier, a lawyer for the Morettis, said he was "surprised" by the former fire safety official remaining silent, while noting that "it is his right" to do so.
"The Morettis...have never refused to answer a single question. They have always been fully cooperative, and that remains the case today and will continue to be," Meier told AFP.
Crans-Montana is in Switzerland's southwestern Wallis canton and the hearings are taking place in the cantonal capital Sion.
Jacques Moretti was due to be questioned again on Tuesday but the hearing was postponed indefinitely on medical grounds.
Prosecutors believe the fire started when champagne bottles with sparklers attached were raised too close to the ceiling in the bar's basement level, igniting the sound insulation foam.
The municipality triggered outrage on 6 January when it revealed that no annual safety check had been carried out at the bar since 2019.
Crans-Montana Mayor Nicolas Féraud is due to face questioning in the coming days.
