Sources familiar with the situation tell TMZ ... the band, which hasn't released a stand-alone *NSYNC single since 2002, has been receiving calls from multiple music labels like Warner Music and Universal Music that are eager to learn about the band's current status.

We're told the guys could find themselves in the middle of another bidding war -- this time with the labels possibly wanting a new single or album from the group.

We broke the story ... Live Nation and AEG started reaching out to *NSYNC members a month ago, expressing interest in a reunion stadium tour.

Back in its heyday, the group was signed to JIVE Records, which later was acquired by RCA Records, with whom Justin Timberlake is currently signed. The band as a whole is not currently signed by a label.

The band, which has sold over 70 million records and been nominated for 8 Grammy Awards, has some seriously tempting financial figures on the table to entice all 5 members back on stage.

We chatted with Chris Kirkpatrick earlier this week and he confirmed that reunion talks are underway.

As we previously reported ... this is all in the very early stages and the guys are looking closely at all offers. However, our sources have said not to expect a decision anytime soon, as the reunion stadium tour is at least a year out.