The optical component maker said it was seeking a declaration that it validly terminated the merger with Cisco, after the deal failed to obtain regulatory approval from China within the originally agreed time frame.

Last week, Cisco said it had received the approval from China on Jan. 7 and sought confirmation from the Delaware Court of Chancery that it has met all conditions for closing the deal.

Acacia, in response, said on Monday that an email dated Jan. 7 from an employee of China's State Administration for Market Regulation stating that Cisco's submission was "sufficient to address the relevant competition concerns", does not constitute regulatory approval.

The company added that it intends to vigorously defend itself against Cisco's claims.

In 2019, Cisco had agreed to buy Acacia to garner a bigger chunk of 5G spending by telecom companies. The deal, which was cleared by the United States, Germany and Austria, had been awaiting regulatory approval from China.

(Reporting by Ayanti Bera in Bengaluru; Editing by Amy Caren Daniel)