The lawyers came to Doha on Saturday night.
A Moscow source earlier said a team of lawyers to protect the arrestees' interests had been made up.
The Russian foreign ministry said yesterday that Russia would provide appropriate legal backing to its imprisoned nationals.
"Russia is intent on protecting the interests of its nationals who are in custody in Qatar, including by providing legal assistance," the ministry told RIA Novosti.
The foreign ministry said it was seeking to have them released as soon as possible.
Three Russian nationals, who were staying at the Russian embassy in Doha, were arrested in the early hours of February 19. One of the arrestees holds a diplomatic passport and was, therefore, released soon. Moscow admits that the arrestees are secret service officers.
The Qatar authorities accuse the Russians of involvement in the assassination of Chechen separatist leader Zelimkhan Yandarbiyev, who had lived in Qatar for the past four years as a guest of honor of Sheikh al-Thani, the Emir of Qatar, while being not allowed to engage in political activities.