"If they were sincere, they should release Aung San Suu Kyi and other pro-democracy leaders," he added.
He said 13 of the 24 freed political prisoners were from the National League for Democracy (NLD).
They included U Than Htay, who had won elections to be a member of parliament in 1990. The NLD won those elections but the military refused to hand over power.
Aung San Suu Kyi, the party's leader and Nobel Peace Prize winner, has been under house arrest since May 30, 2003.
She has spent about 11 out of the last 16 years in custody.
Nyan Win, a spokesman for the NLD, said the party "welcomed the release of prisoners but we are very disappointed that elderly, sick and long-term prisoners are not among those released today".
Two of those released were members of the Karen National Union who had been in prison for more than 20 years.
According to Ko Bo Kyi, although the military government has released over 20,000 inmates since 2004, less than 300 were political prisoners.
His group estimates that more than 100,000 convicts, including 1,100 political detainees, are held in 42 prisons and 91 concentration camps in Myanmar.
Myanmar, formerly known as Burma, gained independence from Britain on January 4, 1948 after more than 120 years of colonial rule.
The country has been under military rule since 1962.