"We have received information that things might happen that will lead to a national security crisis", Anil told reporters in the capital, Male.
The combined opposition said in a statement that it feared a military takeover of the Indian Ocean archipelago to preserve Yameen's grip on power.
But the Yameen government has so far refused to complywith the shock ruling, resisting global pressure.
"The Supreme Court's ruling means that I can finally go back home".
"Security services must uphold the constitution and servethe Maldivian people".
Anil added the security forces have learned that "the Supreme Court may issue an order to impeach the president". Meanwhile, several officials, including two police chiefs and the prison chief have resigned or been sacked, reportedly for seeking to implement the Supreme Court's orders.
Yameen took over as the president after winning a controversial runoff against Nasheed.The Maldives was plagued by political unrest in 2015 when Nasheed, the first democratically elected president of the country, was arrested on "terrorism" charges, relating to the arrest of a judge during his tenure.
The Supreme Court also ordered the release of former defence minister Mohamed Nazim, MP Faris Maumoon, former vice president Ahmed Adheeb, former prosecutor general Muhthaz Muhusin, chief magistrate Ahmed Nihan and local businessman Hamid Ismail.
Police said in a statement they were looking to arrest Saeed over an investigation into apartment purchases but the Supreme Court later annulled the police warrant against Saeed, calling it "against established legal procedure".
In the 2013 Maldives elections, contested between Abdulla Yameen and Mohamed Nasheed, the former took power.
News agencies have reported that the Maldives has seen political unrest and street protests since Nasheed was convicted in 2015 on terror charges and sentenced to 13 years in jail while Nasheed himself was earlier granted asylum by the United Kingdom after he was authorised to seek medical treatment there amid mounting foreign pressure.
The ruling brought opposition activists onto the streets in celebration, sparking clashes with police who fired tear gas to disperse the crowd.
However the authorities shut parliament indefinitely on Saturday to avert such a move. He has since been living in Sri Lanka.
The nation is made up of 26 coral atolls and 1,192 individual islands, and is popular among foreigners as a luxury tourist destination.
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