Video footage of the mutiny by the country's border guards shows "outsiders wearing BDR (Bangladesh Rifles) uniform", a senior army official has alleged.
The new BDR chief Brigadier General Mohammed Mainul Islam referred to "unknown people" who did not belong to the force, while talking to The Daily Star newspaper on Tuesday, reinforcing the government charge of "a conspiracy by outside forces".
The officer is part of the high level probe looking into the insurrection Feb 25-26 in which thousands of BDR troopers stormed into an officers' conference and went on a killing spree.
Over a hundred Bangladesh Army officers who man the paramilitary force from the top down to the battalion level, were shot dead or bludgeoned.
Prime Minister Sheikh Hasina, who weathered the first serious challenge to her nascent regime, on Monday said "conspiracy and evil designs are still being hatched after the bloody BDR mutiny in a bid to foil the country's democracy, independence and sovereignty."
"Perhaps, many did not like the end of the crises...so conspiracy and evil designs are still being hatched," she said in her first public remarks outside parliament since the BDR troopers mutinied at their headquarters on Feb 25.
Saying that conspiracy against Bangladesh has not yet ended, Hasina said: "Plot is still on to foil the country's democracy, independence and sovereignty". She urged all to be alert about such "evil game and conspiracy".
Hasina, under higher security since the crisis, said: "I don't know whether I could speak here today... We won't allow any game with the people's fate."
However, her political rival and Leader of the Opposition, Begum Khaleda Zia, remains unimpressed.
She demanded that Home Minister Sahara Khatun, under whose charge the BDR falls, must resign.
She also demanded that the government withdraw the general amnesty to the rebels that Hasina announced on Feb 25. She has called it "a great strategic mistake".
The government has explained that it was needed to bring an early end to the rebellion.
It has also said that it would continue with the trial of "war criminals" of the 1971 freedom movement, a decision based on Parliament's resolution, that is aimed at the top leaders of the Jamaat-e-Islami, the country's largest Islamist party.
Jamaat's chief Motiur Rahman Nizami is accused of being one of those who killed civilians on behalf of then East Pakistan regime. Jamaat secretary general Ali Mujaheed was last month prevented from leaving for Saudi Arabia.
"No conspiracy can cause the government to deviate from its desired goals, including the trial of war criminals," Commerce Minister Col. (retd) Faruk Khan told media on Monday.
This move is widely perceived as the reason why the so-called "outside forces" instigated the BDR insurrection.
Meanwhile, authorities found four more bodies of the BDR mutiny victims, including an army officer. The number of missing officers is now five.
BDR troopers complained of bad pay and working conditions and alleged discrimination vis a vis the army. All but six men in uniform killed during the mutiny were middle and junior level army officers.