WARSAW, Poland (AP) _ Twenty-two communist-era riot policemen went on trial Wednesday for the second time on charges of killing nine miners who resisted Poland's 1981 martial-law crackdown.

The retrial, at the district court in the southern city of Katowice, was ordered last year after the Supreme Court found procedural mistakes in the original trial, in which the defendants were acquitted.

The nine miners killed on the third day of martial law were the first fatalities in the 1 1/2-year crackdown, which claimed the lives of 100 government opponents before it was lifted in July 1983.

The miners were protesting the loss of basic freedoms and the jailing of Solidarity union leaders when martial law was imposed Dec. 13, 1981.

When several hundred miners who had barricaded themselves in the Wujek and the Manifest Lipcowy mines wouldn't budge on the third day, riot police opened fire, killing nine and wounding 25.

More than 2,000 police, a dozen tanks, armored vehicles and water cannon were used to suppress the strike. It was the worst bloodshed of the martial-law period.

The defendants contended that they had fired into the air, well above the heads of the protesters.