Poland's last communist leader, General Wojciech Jaruzelski, and seven other Soviet-era officials went on trial on Friday over the declaration of martial law more than a quarter of a century ago.

Poland's National Remembrance Institute accuses the defendants, now grey-haired elderly men, of violating the law and flouting human rights with the 1981 decision, which led to the deaths of dozens of people and the jailing of hundreds more.

The defendants deny the accusations, saying they acted out of "higher necessity" to silence the anti-communist Solidarity trade union and avert a threatened Soviet invasion of Poland.

Solidarity, led by shipyard electrician and later Nobel Peace Laureate Lech Walesa, played a leading role in overthrowing communism in Poland eight years later.

Jaruzelski has often argued that the imposition of martial law spared Poland the bloody Soviet intervention suffered by Hungary in 1956 and the then-Czechoslovakia in 1968.