An Albanian court on Monday sentenced 18 officials and army officers to jail over an explosion that killed 26 people at an ammunition disposal plant, but angered the victims' relatives by clearing three defendants of murder charges.

Tirana's District Court judge Ridvan Hado had been hearing the case of 28 defense ministry officials, high-ranking army officers and the two businessmen who ran an ammunition dismantling plant at Gerdec whose 400 tons of ammunition exploded in a ball of fire on March 15, 2008.

The court issued the guilty verdicts for 18 defendants, sentencing them to between one and 18 years on charges of gross mismanagement and related offenses.

Ylli Pinari, the defense ministry's trading firm director, and Dritan Minxolli, the businessman in charge of the dismantling plant, received 18 year sentence.

Mihal Delijorgji, the owner of the company dismantling ammunition, was sentenced to 10 year in jail.

The prosecution had asked for life in jail for the three defendants, accused of multiple murders, but the court did not mention the manslaughter charge in its verdict.

Zamira Durda, the mother of a six-year-old who was killed in the explosion and who has become a symbol of the victims' families seeking justice, expressed her anger by blocking the door of the court for several minutes and crying out loudly, saying she felt her boy had been "killed again today."

The families of the victims regretted in a statement that the court had ruled on smaller offences like abuse of office and destruction of property but failed to find out who was responsible for the deaths of their relatives.

"The name of who killed our loved ones still remains an enigma. We were the subject of mass murder four years ago and those responsible should have been judged for that crime," the families said in a statement issued by their lawyer.

"We hoped to see justice done: it was not only delayed but also failed. The families of the victims of the Gerdec explosion still want to know today who killed our loved ones," they added.

The plant in Gerdec, a village on the highway near the capital Tirana and the main international airport, had been dismantling bullets and artillery shells from the old stocks of the Albanian army.

The heat from a welded wheelbarrow ignited the gunpowder, setting off a number of explosions, which also injured 300 people and damaged houses.

Delijorgji and Minxolli blamed a conspiracy meant to delay Albania's NATO membership, but it was not affected and Albania joined NATO a month and a half later.

However, many in the chain of command of the armed forces had to stand down. Former defense minister Fatmir Mediu, now the environment minister, resigned.

Despite accusations from the victims' families, Mediu was not tried after he was re-elected to parliament and prosecutors did not renew their request to lift his immunity from persecution.

Luan Hoxha, the former chief of staff of the armed forces, was sentenced to six years in jail, but he has reportedly left Albania. Another army chief had his three-year sentence suspended.