Maskhadov, a 53-year-old separatist chief who at one time had been chosen as Chechnya's president in a widely-recognised election, was killed on 8 March in a village north of the capital Grozny.
Russia, which had branded him a "terrorist", said his body would not be released for burial to his family because current legislation calls for "terrorists" to be buried in unmarked graves.
Burial is one of Chechnya's most sacred traditions and Moscow's refusal to return the body of Maskhadov - whom a court has never convicted on terrorism charges - has sparked dissent even from the pro-Kremlin government in Chechnya.
On Monday, rights activists added their voice to the controversy.
"We think it shameful the refusal to return the remains to relatives for burial," said a statement signed by several leading human rights groups including Lev Ponomaryov of For Human Rights.
"We support Maskhadov's relatives' claim for his body," said the statement.
"We think it shameful the refusal to return the remains to relatives for burial"
Human rights groups
Following his death, Maskhadov's wife and two children appealed to the West to try and pressure Russian President Vladimir Putin to return the body for burial.
News reports on Friday said Maskhadov's body was currently in Moscow for further identification.
Maskhadov, who was elected Chechnya's president in January 1997 in an election called free and fair by European observers and recognised by Russia, was the only major separatist chief who advocated negotiations to end the current war in Chechnya, which Moscow launched in October 1999.