POLICE are investigating the sudden death of Gwent-born Dr Phil Williams, one of Plaid Cymru's most respected politicians and a respected scientist, found in a massage parlour yesterday.

Dr Williams, former shadow Welsh economic development minister, was found dead in Cardiff massage parlour A Touch of Class.

Senior sources confirmed Mr Williams died there and police have been guarding the site since last night.

Born in Tredegar in 1939, he grew up in Bargoed and went to Cambridge University. His standing as a leading light of Plaid Cymru was established in 1968 when he stood in the Caerphilly parliamentary by-election and slashed the Labour majority from 20,000 to 2,000.

He stood against Peter Law for the Blaenau Gwent on the National Assembly for South Wales East in 1999 but became an AM for South Wales East.

Mr Law described it as a very good natured campaign. "I respected him greatly. He understood the problems of the Valleys because he was a Valleys boy. He had a brilliant brain and in Assembly debates he would be flying at 100,000 ft while the rest of us were hedge-hopping.

"Outside the political arena he was a person whose company I enjoyed very much. He will be sadly missed. He had a lot more to give to his party."

The former chairman of the Welsh nationalists was voted Welsh politician of the year in a Channel 4 competition but stood down at the last election in 2003 and returned to academic life.

The saxophone-playing scientist taught solar terrestrial physics at Aberystwyth University.

Dr Williams, 63, had been under pressure to take over as Plaid Cymru's president after Ieuan Wyn Jones announced he was to quit.

South Wales Police confirmed yesterday they were looking into his death in Cardiff but they are not treating it as suspicious.

Plaid Cymru leader Ieuan Wyn Jones said: "I have known Phil Williams for over 30 years and always knew that I was in the presence of a genius."