Rampant police corruption is impeding Liberia's development a decade after its 14-year civil war ended, and abuses should be reined in as the United Nations scales back its presence in the West African country, Human Rights Watch said.

Underpaid and inadequately supplied, Liberian police officers demand bribes at every stage of an investigation, the human rights group said on Thursday in a new report, "No Money, No Justice".

They extort money from taxi drivers and motorcyclists and steal from street vendors, while criminal suspects routinely pay bribes to get released, the report said.

The United Nations, citing a lack of professionalism and resources in the police force, recommended in February that the government allocate more resources to law enforcement to ensure that Liberia's security sector gains the trust of its citizens and can operate independently once the U.N. mission withdraws.

"Improving the criminal justice system, addressing impunity for crimes and increasing access to justice and security services for all Liberians remain particularly important for the consolidation of peace," the U.N. Mission in Liberia said in its report to the Security Council.

U.N. peacekeepers went into Liberia in 2003 to stabilize the country after years of civil war led to a collapse of the state. It was carved up by warlords who used child soldiers to fight over control of diamond and timber concessions.

After 10 years of peacekeeping efforts, the United Nations is gradually drawing down its troops in Liberia from about 8,000 to 3,750 by July 2015.

"Liberians have had all too many years of chaos and violence. A professional police force is critical to uphold people's rights and create a rights-respecting society," said Corinne Dufka, Human Rights Watch's senior West Africa researcher.

'THE MAJOR PUBLIC ENEMY'

The group called on President Ellen Johnson Sirleaf's government to establish a civilian oversight board, immediately investigate resource shortages in the police force, improve the system for reporting police abuse and strengthen the Liberia Anti-Corruption Commission, which struggles to get convictions.

The report was based on interviews with 120 people and 35 police officers of all ranks. In one account, a resident of the capital, Monrovia, said that the elite Police Support Unit came to his home, kicked him, held his wife at gunpoint and stole money she had hidden in her bra.

When Johnson Sirleaf took office in 2006, she called corruption "the major public enemy". Her administration has made some progress in improving arrest procedures and addressing violence against women, Human Rights Watch said.

But corruption and abuses persist, denying ordinary Liberians access to justice and money to support their families and frustrating the attempts of people trying to rebuild their lives after the war that killed more than 200,000 people and displaced another million, it said.

In the report, the police expressed their own frustration over inadequate supplies, low salaries and pressure to pay their superiors to obtain desirable posts and promotions.

"They come crying to you and you don't even have a drop of gas," the report quoted one officer as saying when describing the difficulty of traveling to a crime scene. "We are not supposed to ask someone for money, but because you don't have (gas), we ask the person for money to go."

"These actions violate Liberians' rights under international and national law and undermine public trust in the Liberia National Police," Dufka said.