Adding to a catalogue of alleged crimes for which the 36 are on trial, prosecutor Said al-Aqil told a Sanaa court that the accused had also planned to kill high-ranking army officers.

The defendants, eight of whom are being tried in absentia, are accused of carrying out a spate of attacks on soldiers and military vehicles in Sanaa in recent months, in which one officer was killed and 27 other people wounded.

The Zaidis are a Shia Muslim sect dominant in northwestern Yemen but overall in the minority in the mainly Sunni country.

President Salih has accused Zaidi rebels of seeking to overthrow his republican government.

Hundreds have been killed in fierce fighting between the rebels and government forces in the country's northwest.

Two rounds of fighting in Saada province last year and again in March-April involved rebels from the Faithful Youth movement of slain radical preacher Husain al-Huthi, who was killed by the army last September after leading a nearly three-month uprising.

The rebels reject as illegitimate the republican government which seized power in a 1962 coup, overthrowing the Zaidi imam.