The board of Cision unanimously recommended Blue Canyon's 52 Swedish Krone per share offer to shareholders on 14 February.
Meltwater has lodged a cash bid at 60 Swedish Krone per share, valuing Cision at approximately 895 million Swedish Krone (£83 million).
Meltwater said it had made the bid without first requesting a recommendation from the board of Cision because it wanted Cision shareholders to know about it before tomorrow, when the acceptance period for Blue Canyon's bid expires.
It has already demonstrated the seriousness of its intent by buying 15.3 per cent of Cision since Blue Canyon's bid was recommended.
Blue Canyon is the name of the investment vehicle through which US-headquartered private equity firm GTCR is seeking to acquire Cision.
Meltwater's founder and CEO Jorn Lyseggen said: "We believe in the industrial logic of combining Meltwater and Cision. We believe that together we will be in a position to offer clients better services combining the world’s best media intelligence services and the world’s premier journalist contact database."
Update [4 April]: Cision's chairman Hans-Eric Andersson declined to comment.