Dame Elizabeth Taylor is to undergo surgery to repair a leaky heart valve, the veteran actress announced via Twitter today.

The 77-year-old called on supporters to pray for her as she explained in a series of messages the procedure to be carried out at an undisclosed hospital.

"I'll let you know when it is all over. Love you, Elizabeth," the last of three messages on the subject read.

The Oscar-winner's last high-profile appearance was made last month at the funeral of long-time friend Michael Jackson.

But it was a rare public outing for the actress who has suffered from a number of ailments in recent years and is now seen in a wheelchair.

She was taken to hospital last May for what her publicist described at the time as a routine check-up.

After being released from the Los Angeles clinic she announced via Twitter that she was "home from the hospital and feeling great".

Dame Elizabeth again used the micro-messaging site to give details of her new date with the doctors.

She tweeted: "Dear friends, I would like to let you know before it gets in the papers that I am going into the hospital to have a procedure on my heart."

The next post explained: "It's very new and involves repairing my leaky valve using a clip device, without open heart surgery, so that my heart will function better."

In a final tweet on the subject Dame Elizabeth added: "Any prayers you happen to have lying around I would dearly appreciate. I'll let you know when it's all over. Love you, Elizabeth."