Arnold Schwarzenegger and Maria ShriverGetty Images

Arnold Schwarzenegger and Maria Shriver - who tied the knot in 1986 - split three years ago and she filed for divorce in July 2011 following revelations he had fathered a son, who is now 16, with their housekeeper Mildred Baena.

A source told MailOnline: "It's been a long road, for a long time it wasn't a priority for either of them, but the divorce is almost complete. The lawyers are just ironing out the final details.

"If everything goes to plan it should be tied up by Christmas."

Arnold, 67, and Maria, 58 - who have four children together, Katherine, 25, Christina, 23, Patrick, 21 and Christopher, 17 - have come to an "amicable" agreement over their $400 million fortune, although it hasn't been an easy process.

The source added: "It has been a long legal process and not an easy one by any means, but Maria and Arnold are now amicable and have reached an agreement.

"When you have large fortunes to divide and legacies for the children to agree on, things aren't always as clearly defined as you'd imagine.

"But Maria and Arnold have resolved their differences and are on speaking terms, they have four kids together after all.

"They are both in a good place and ready to move on."

Hollywood star Arnold is said to be worth $300 million while NBC News anchor Maria - who is the niece of former US President John F. Kennedy - is estimated to be worth $100 million.

In Californian law, she is entitled to half of his earnings throughout their marriage.

In May 2011, Arnold admitted sleeping with their housekeeper and fathering her son, saying at the time: "There are no excuses, and I take full responsibility for the hurt I have caused."

Maria has since moved on with boyfriend Matthew Dowd, who she was spotted out in public with for the first time at Robert F. Kennedy Jr. and Cheryl Hines' wedding last month.

This comes after it was reported last week that former Governor of California Arnold had an artist paint over the image of Maria's face on his official political portrait.