MADRID (Reuters) - Spain's High Court sentenced 20 Islamic radicals to between five and 14 years in jail on Wednesday on charges linked to the formation of a group whose leader plotted to blow up the court's Madrid building.

Abderrahmane Tahiri, a Moroccan described by the court as "nearly obsessed" with his plan to kill Spanish judges by bombing the High Court in Madrid, was sentenced to 14 years for forming the terrorist group he led.

The court said in its ruling that no evidence had been found that the plot had got beyond Tahiri's imagination.

Apart from Tahiri, 17 men received jail terms for being members of a terrorist group and two men were sentenced for assisting terrorists.

Thirty suspects arrested in October 2004 had been charged with crimes linked to the plot to blow up the High Court. Most were from Morocco and Algeria.

In March 2004, a separate group of Islamist bombers killed 191 people in attacks on Madrid trains, for which 21 men were jailed. Spanish police have since regularly arrested suspected Islamist militants and in January arrested 14 South Asians suspected of plotting to attack Barcelona's Metro subway.

Prosecutors had asked for sentences from 8 to 43 years for the High Court plot.

(Reporting by Teresa Larraz; Editing by Charles Dick)