(Reuters) -Skydance Media is accusing Paramount Global's ( PARAA ) special committee of directors of breaching the terms of its deal by extending the period of time when it can engage with other bidders, the Wall Street Journal reported on Thursday.

This comes after veteran media executive Edgar Bronfman Jr sweetened his bid to take over Paramount offering $6 billion for its controlling shareholder National Amusements and a minority stake in Paramount.

Bronfman's competing offer threatens to undo a planned acquisition by tech scion David Ellison and his independent studio Skydance Media.

Shares of Paramount, the home of Paramount Pictures, the CBS broadcast network and cable networks such as MTV, were down 1.5% in extended trading.

"While Skydance is not currently exercising its right to terminate the transaction agreement, we reserve the right to do so in the future," the report quoted Skydance's attorneys as saying in a letter.

Paramount's special board committee and a spokesperson for Bronfman declined to comment. A spokesperson for Skydance Media could not immediately be reached.

The special board committee extended the Aug. 21 "go-shop" period deadline until Sept. 5 for Bronfman's consortium, Paramount had said on Wednesday.

If Paramount, controlled by Shari Redstone's family business, accepts an offer that Skydance does not match, the media conglomerate would have to cough up a $400 million in break-up fee.