The parties had gathered at an Opposition rally called by Arvind Kejriwal earlier in the day.
The Opposition parties on February 13 stated that they would enter into a pre-poll alliance and decide upon a common minimum programme for the upcoming Lok Sabha polls.
Top Opposition leaders, including Congress President Rahul Gandhi, Nationalist Congress Party (NCP) chief Sharad Pawar, Telugu Desam Party (TDP) supremo Chandrababu Naidu and Delhi Chief Minister (CM) Arvind Kejriwal met at Pawar's residence in New Delhi earlier in the evening.
Addressing the media after the meeting, West Bengal CM and Trinamool Congress chief Mamata Banerjee said that the parties have decided to "work together at national level." She also added that the Opposition parties would be meeting at regular intervals and will hold a meeting in Amravati on February 26 to decide on a strategy.
"We had a very constructive meeting. We agreed that principal target for all of us is to fight against the assault on institutes being carried out by the BJP," Rahul Gandhi said. The Gandhi scion, however, said that the parties did not discuss potential alliances in West Bengal and Delhi.
"We will cooperate, yet compete with each other... In Delhi, we will decide later and in West Bengal... The broader arrangement is to work together at national level," Gandhi said.The parties had gathered at an Opposition rally called by Kejriwal earlier in the day.