Kinshasa - Congolese state security forces have killed an estimated 500 people seen as opponents to President Joseph Kabila and detained another 1,000 in the two years since internationally backed elections brought him to power, Human Rights Watch (HRW) said Tuesday.

"While everyone focuses on the violence in eastern (Democratic Republic of) Congo, government abuses against political opponents attract little attention," said Anneke Van Woudenberg, senior researcher in the Africa division of Human Rights Watch.

"Efforts to build a democratic DR Congo are being stifled not just by rebellion but also by the Kabila government's repression," she added.

In a 96-page report, "We Will Crush You: The Restriction of Political Space in the Democratic Republic of Congo," HRW said that Kabila gave orders to "crush" or "neutralize" the "enemies of democracy."

Kabila came to power in 2006 after elections that were supposed to bring stability to a country still in tatters after the 1998-2003 war, which UN agencies say caused the deaths of over 5 million people.

However, the elections themselves were marred by violence and armed clashes have continued in the east of the sprawling nation despite Kabila taking over the reins of powers.

Fighting between Tutsi rebels loyal to rebel general Laurent Nkunda, which has simmered for years, and government troops exploded into full-scale conflict in October after beginning to ramp up in August.

Over 250,000 civilians have been displaced since August as results of the clashes, creating the potential for a humanitarian catastrophe, aid agencies say.

However, in western DR Congo, Kabila's subordinates - working through the paramilitary Republican Guards, the police and the intelligence services - have quietly been cracking down on political opponents, HRW said.

According to HRW, supporters of Jean-Pierre Bemba, one of the defeated presidential candidates, and members of other political parties were targeted.

The bodies of those summarily executed were dumped in the Congo River or secretly buried in mass graves, HRW found after conducting hundreds of interviews with officials, victims and witnesses.

"They (republican guards) took 10 of the prisoners, tied their hands, blindfolded them, and taped pieces of cardboard over their mouths so they couldn't scream," one witness, who was being held in a military camp, told HRW in the report.

"The captain ... took them away ... I knew one of the guards and asked what had happened. He said the others had been taken to the [Congo] river near Kinsuka and killed," the witness continued.

Detainees were beaten, tortured and forced to sign confessions saying they were involved in coup attempts against Kabila, witnesses told HRW.

"They gave me electric shocks all over my body. They put the electric baton in my anus and on my genitals ... I cried so much that I could hardly see any more. I shouted I would sign whatever they wanted me to," a former detainee held at Kin-Maziere prison said.

HRW, which said that foreign governments deliberately buried reports on the repression, called for a high-level task force to document the abuses and secure the release of those being held illegally.

"The Congolese people deserve a government which will uphold their democratic rights, not one that represses opponents," Van Woudenberg said. "An important first step would be to bring to justice those officials responsible for killings and torture." (dpa)