MIAMI, US (AFP) - US federal prosecutors have asked for prison sentences of between 30 and 70 years for five members of a homegrown terrorist group accused of plotting to blow up the Sears Tower in Chicago, court documents showed Tuesday.

In court filings prosecutors called for the group's leader Narseal Batiste to be given the maximum penalty of 70 years in prison, 50 years for another member Patrick Abraham, and 30 years for the other three.

The court should "impose sentences on these defendants that are consistent with the verdicts and the seriousness of their crimes," prosecutors said in their filing ahead of Wednesday's sentencing.

A US jury in May convicted the group of seeking to contact Al-Qaeda and plot a series of attacks, including blowing up the Sears Tower in Chicago and FBI buildings, to bring down the US government.

Two previous trials ended in hung juries.

Batiste, 35, was convicted on four counts of conspiracy, including providing material support for a foreign terrorist organization, conspiring to provide material support for terrorists, conspiring to blow up buildings with explosives and conspiring to commit seditious acts.

Abraham, 29, was convicted on three counts of conspiracy and faces up to 50 years in prison. The three others were convicted of two counts of conspiracy.

Another of the accused, Naudimar Herrera, 25, was found not guilty of the conspiracy charges, and a seventh member of the group was acquitted in an earlier trial.

Dubbed the "Liberty City Seven" after a predominantly Haitian and African American Miami suburb, the group was arrested June 22, 2006 in a raid on warehouse on the outskirts of Miami.

Defense lawyers portrayed the FBI sting operation and ensuing arrests as a play for publicity to highlight the government's campaign against terrorism in the United States.