In its latest bid to gain complete control of the British satellite service BSkyB, Rupert Murdoch's News Corp on Wednesday offered to sell or spin off its Sky News channel. Such a maneuver, analysts indicated, is intended to relieve concerns about media control that have been expressed by Murdoch's rivals and by consumer groups. But on Wednesday they continued to voice their opposition to Murdoch's plan to purchase the 61 percent of BSkyB that News Corp doesn't already own for more than $12 billion. An alliance of newspaper groups that have opposed News Corp's bid said, "We have real doubts about the purported remedy."