Left: A file picture taken on November 9, 2013 shows US actor George Clooney attends the 2013 BAFTA LA Jaguar Britannia Awards presented by BBC America at The Beverly Hilton Hotel in Beverly Hills, California. Hollywood heartthrob George Clooney, one of Hollywood's most coveted bachelors, has got engaged to his British lawyer girlfriend Amal Alamuddin. Right: A file photo taken on Nov 5, 2012 shows British laywer Amal Alamuddin attending a press conference in London on November 5, 2012. [Photo/CFP]

George Clooney is planning to retire

George Clooney still looking for the love of his life

Media speculation that Clooney had gone back on his vow never to remarry grew at the weekend after his girlfriend, human rights lawyer Amal Alamuddin, was spotted wearing a large ring on her wedding finger at a Los Angeles restaurant.

The couple have said nothing and Clooney's representative declined to comment on the actor's personal life, but on Monday Alamuddin's law firm released a statement.

"The barristers and staff of Doughty Street Chambers offer their best wishes and congratulations to Ms Amal Alamuddin, a member of Chambers, and Mr George Clooney on their engagement to be married," the firm said.

Clooney, 52, and Alamuddin, 36, have been dating since last October, according to media reports.

Clooney, a two-time Oscar winner and human rights activist, has been married once, but since his 1993 divorce from Talia Balsam has remained one of Hollywood's most eligible bachelors.

Apart from his acting, Clooney has also recently worked as an advocate for refugees in Darfur in Sudan.

"BRIGHT LIGHT"

The London law firm said it had recruited Alamuddin in 2010 to complete her training as a barrister in England and she later became a full member, joining its international law team.

She was educated at St Hugh's College, Oxford University, and New York University School of Law and speaks Arabic and French fluently, according to the law firm's website.

Alamuddin has advised United Nations former secretary-general Kofi Annan on Syria, represented Ukraine's ex-prime minister Yulia Tymoshenko in challenging her detention before the European Court of Human Rights and has also represented WikiLeaks founder Julian Assange in extradition proceedings.

Alamuddin drew publicity last year when she was named as topping an online "hot list" of attractive female barristers in Britain.

Barrister Geoffrey Robertson, who took Alamuddin on at Doughty Street chambers and worked with her on the Tymoshenko and Assange cases, described her as a "brilliant and passionate defender of human rights" who was respected by her colleagues.

The chief executive of her law firm, Robin Jackson, added his personal congratulations.

"She brings a bright light to everything she is involved in, and I am so delighted at her happy news," he said.