Skysports.com understands Colchester have rejected an offer from Charlton for Magnus Okuonghae.
The 25-year-old defender has produced a series of impressive performances for Colchester since arriving from Dagenham & Redbridge in 2009.
His fine form has not gone unnoticed, though, and Charlton are believed to have lodged a bid for his services.
Although the offer was turned down, the Addicks are now thought to be poised to make a second approach.
Okuonghae is also understood to have attracted interest at Championship level and it remains to be seen where his future lies.