Ms Banerjee's remark came after the Telugu Desam Party or TDP this morning formally decided to exit the Narendra Modi government over the Centre's refusal to grant Andhra Pradesh Special Category Status (SCS).
"I welcome the TDP's decision to leave the NDA. The current situation warrants such action to save the country from disaster," the Trinamool Congress chief said in a tweet.
"I appeal to all political parties in the Opposition to work closely together against atrocities, economic calamity and political instability," Ms Banerjee said.
The party's politburo unanimously took the decision during a tele-conference with party chief and Andhra Pradesh Chief Minister N Chandrababu Naidu.