Jessica Biel has been spotted wearing an apparent engagement ring.

The actress reportedly became betrothed to her on-off boyfriend Justin Timberlake last Christmas but has so far not been seen wearing a traditional sparkler.

However, last Saturday the brunette beauty attended a Saturday Night Live celebration in New York City with her beau and was wearing what appeared to be an engagement band.

According to a source, the couple looked loved-up and affectionate all night.

"[They] were very lovey all night and kissed a few times," a guest at the Ristorante Asellina party told US publication People.

No further details about the ring have been reported.

Actress Kristen Bell was also in attendance at the SNL do and was spotted quizzing Jessica about the piece of jewellery.

"[She] loved the ring and chatted [Biel] up about it," the source added.

Jessica and Justin started dating in 2007 following the singer-and-actor's break-up from actress Cameron Diaz.

After a brief split in 2011 the couple reunited and Justin is believed to have proposed on a pre-Christmas holiday in Wyoming last year.