The team posted a story on its Web site saying it had signed the former Indianapolis Colts safety, but Chargers spokesman Bill Johnston said that report was premature and no announcement was planned Thursday night.
The person with knowledge of the deal said it wasn't clear when Sanders actually can sign a contract because of the status of labor talks. The NFL and its players' union decided Thursday to keep the current collective bargaining agreement in place for an additional 24 hours so negotiations can continue.
Once Sanders does sign, the Chargers hope to have the hard-hitting safety, not the one who has missed 64 games -- the equivalent of four full seasons -- because of injuries in his seven-year NFL career. He has played in just 48 regular-season games.
After winning the 2007 NFL Defensive Player of the Year Award, Sanders signed a five-year, $37.5 million contract with the Colts but played in just nine regular-season games during the next three seasons. He tore his right biceps on the first defensive series in the 2010 season opener and didn't play again.
Weddle's agent, David Canter, told The San Diego Union-Tribune that he's "absolutely baffled we haven't had a conversation" about a new contract, although the free safety was sure he'd return to the Chargers unless another team makes a huge offer and is willing to sacrifice a first-round draft pick to sign him.
"I ultimately think it will get done and I'll be here," Weddle said of a long-term deal. "But by no means -- if it's way off, I'm not going to be here."
Weddle, a four-year pro, has 358 tackles, six interceptions (two returned for touchdowns) and 28 passes defensed during his San Diego tenure. He has been a regular starter since his second NFL season.
The Associated Press contributed to this report.