"There is close cooperation between us on the supply of military products, including aircraft," Alexander Mikheev, the head of Rosoboronexport, was quoted as saying by the Interfax news agency.
He gave no further details.
Mikheev described Myanmar as one of Rosoboronexport's main clients in south-east Asia and a key partner of Rostec, Russia's state aerospace and defence conglomerate.
He made the comments at Russia's annual MAKS air show, which president Vladimir Putin attended on Tuesday.
Russian defence minister Sergei Shoigu told Myanmar's junta leader senior general Min Aung Hlaing during his visit to the Russian capital last month that Moscow was committed to strengthening military ties.
Defence ties between the two countries have grown in recent years with Moscow providing army training and university scholarships to thousands of soldiers, as well as selling arms to a military blacklisted by several Western countries.