Lindsay Lohan has been seen wearing an engagement ring.

The "Mean Girls" actress has reunited with her on/off girlfriend, DJ Samantha Ronson - who she split from earlier this year - and has been spotted with a huge diamond on her ring finger, sparking rumours they are engaged.

The couple were photographed together at London's Heathrow airport on June 8 where they boarded a plane for Los Angeles.

Lindsay has further fuelled reconciliation rumours by posting a cryptic message on her Twitter page.

She wrote: "Leaving London but with my favorite favorite!!!-travel buddy+great news to share!! Maybe.... ;) (sic)"

After reuniting at the airport Lindsay and Samantha reportedly demanded to sit together and walked to the first class lounge holding hands.

The 22-year-old Hollywood star and Samantha, 31, stayed in separate hotels during their UK break and were hardly seen together during the trip, despite Lindsay's desperate attempts to track the DJ down last Wednesday evening.

Friends of the couple - who have dated on and off for two years - have confirmed their relationship is back on.

One pal said: "They haven't started fighting yet, but they are back together as far as Lindsay is concerned. Lindsay has been doing so much better and has been giving Samantha her space. She is really dedicated to making it work."

(China Daily/Agencies June 10, 2009)