Reality star Heidi Montag has filed for divorce from her estranged husband Spencer Pratt. The 23-year-old beauty walked out on her former reality TV co-star in May and filed for legal separation last month. She has now lodged a divorce petition.

In Santa Monica, California Superior Court, citing irreconcilable differences, People reported online. Montag shot to fame by starring in reality series 'The Hills' where she met Pratt. In November 2008, the couple eloped in Mexico, though they later married in US in April 2009.

"Heidi has amended her petition for separation and today has filed a petition for dissolution of marriage from Spencer Pratt. The couple has agreed they would like their divorce to be finalised in a timely manner in an out-of-court settlement.

Both parties are amicable with each other and over the possibility of finalising their divorce," said Montag's lawyer, Jodeane Farrell. "I love Heidi but our marriage was a show  it was part of The Hills world, and that world is on a sound stage," said Pratt.