Washington DC - An animal rights activist who was on the FBI's most wanted terrorist list and has been on the run for more than 20 years has been arrested in Wales, the FBI said Tuesday.

Daniel Andreas San Diego (46), who was wanted in connection with three bombings in California in 2003, was arrested on Monday, the bureau said in a statement.

"Daniel San Diego's arrest after more than 20 years as a fugitive for two bombings in the San Francisco area shows that no matter how long it takes, the FBI will find you and hold you accountable," FBI Director Christopher Wray said.

"There's a right way and a wrong way to express your views in our country, and turning to violence and destruction of property is not the right way."

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San Diego was wanted in connection with pipe bombings in California in August and September 2003 targeting a biotechnology company and a nutritional products corporation.

He was indicted in July 2004 and has been a fugitive since then. He was added to the FBI's most wanted list in 2009 and the bureau offered a $250,000 reward for his capture.

Britain's National Crime Agency said San Diego now faces extradition to the US to face charges.