Robert Pattinson and Kristen Stewart
Robert Pattinson and Kristen Stewart Reuters

Twilight actress Kristen Stewart is considering legal action against former boyfriend and co-star Robert Pattinson, in a battle for custody of their two pet dogs.

Stewart and the Remember Me star became famous after starring together in the hugely successful Twilight series of fantasy vampire-themed films, based on novels of the same name by Stephenie Meyer. The two, who bought mixed breed dogs Bear and Bernie, broke up last year after Stewart cheated on Pattinson with British director Rupert Sanders. Pattinson moved out of the Loz Feliz mansion he shared with Stewart.

Now, 23-year-old Stewart is reportedly upset that Pattinson left the dogs with a friend while he was working in Toronto.

"Things have gotten pretty nasty between Rob and Kristen in recent weeks," a source told Grazia magazine, "And since Kristen found out Rob has left the dogs with a friend, she's seeking lawyers' advice on getting sole custody. She's been warned it could cost up to $100,000 in legal fees."

Relations between the two turned frosty when Stewart heard that the 27-year-old British born actor was dating Riley Keough, granddaughter of Elvis Presley.

"She was gutted when she found out about Rob and Riley," the insider added, "Kristen has started sending friends to pick up the dogs - she couldn't face seeing Rob. No one knows how they're going to work this out or where the dogs will end up."

Previously it was reported that Stewart was seeking joint custody of the dogs.

"Kristen thinks they should have one each. She's missing the dogs like mad, but doesn't want the situation to turn nasty," a source told the Daily Star.