Hundreds of thousands of civilians displaced by conflict in Ivory Coast are avoiding returning home for fear of torture or killing due to their political loyalties, rights group Amnesty International said Thursday.

"Government security forces and a state-backed militia have created a climate of fear in Ivory Coast" since President Alassane Ouattara took over in April, the global watchdog said.

It said refugees had reported summary executions, torture, abuse and arbitrary arrests by national forces and ethnic militias of people accused of loyalty to the ousted former president Laurent Gbagbo.

Fear "is preventing hundreds of thousands of people displaced in the post-electoral violence from returning to their homes," it said.

Forces loyal to Ouattara, with help from the French military, ousted Gbagbo at the end of months of stalemate after Gbagbo refused to accept defeat in a UN-certified election.

Rights groups say at least 3,000 people were killed during the crisis which broke down into violence between the two rival's supporters in different ethnic groups and along a broadly north-south divide.

"An impartial security force must be created that can ensure the protection of all Ivorian citizens, whatever ethnic group they belong to," said one of the Amnesty report's authors, Gaetan Mootoo.

The United Nations High Commission for Refugees says there are half a million displaced people within Ivory Coast and a further 170,000 who have fled across the border to Liberia.

"The victims suffer a double terror: undergoing violence and seeing the authors of that violence go free," said another researcher in the report, Salvatore Sagues.