Published: 2020-09-01 18:49:36 BdST
Myo Swe, a spokesman for the ministry, said it had acted on reports by a social media monitoring group related to the security forces but declined to name the group.
The campaign group whose website was blocked, Justice for Myanmar, investigates the military's business interests.
"The social media monitoring team found that some websites are spreading fake news," Myo Swe told Reuters by phone.
A spokesman for the military did not answer calls from Reuters seeking comment.
Justice for Myanmar has published a series of investigations on its website, including a report about businesses that donated to the security forces during a 2017 crackdown on Rohingya Muslims that the United Nations said was carried out with "genocidal intent".
The army denies genocide, saying it was engaged in legitimate operations against militants.
In recent months, the telecommunications ministry has blocked more than 200 websites for disseminating what it deems to be fake news, including agencies that cover conflict between the military and ethnic minority insurgents.
Norway’s Telenor, one of four mobile operators in Myanmar, said in a statement the ministry had invoked Section 77 of the Telecommunications Law, which authorises the suspension of communication during an “emergency”, to order it to block one website and three associated IP addresses.
It did not identify the website but said it had complied with the order and viewed it with “grave concern”. It said it protested against the blocking but did not say to whom.
On Tuesday, Justice for Myanmar’s website not accessible inside the country.
Instead, it was replaced with the message: “You have tried to access a web page which has been blocked as per directive received from the Ministry of Transport and Communications of Myanmar.”
Yadanar Maung, a representative of the group, said in a statement the block was "an attempt to silence dissent and cover up the truth about the Myanmar military cartel’s corruption and international crimes".
"We will continue speaking truth to power."