Power company Mirant Corp. on Wednesday sued rival energy producer NRG Energy Inc., claiming that NRG is unfairly rejecting its nearly $8 billion takeover bid.

Atlanta-based Mirant sought a court order in Delaware directing NRG not to obstruct its attempts to acquire NRG. Mirant asserted that NRG is using a “transaction ploy” to turn aside the offer by claiming that Mirant is using confidential information from NRG’s former financial adviser.