CONTROVERSIAL security company G4S said it was the best firm for the job last night as campaigners called for an urgent rethink on the decision to allow it run a government-funded discrimination helpline.

The multinational, which has a turnover of more than £1.7 billion, has a string of public-sector contracts in the UK managing prisons, children’s homes and immigration centres. It has also been involved in a number of controversies, with staff at a secure youth training centre accused of racism and abuse and workers at an immigration removal centre called “corrupt” by a High Court judge.

The company also faced widespread condemnation for placing asylum-seekers in houses with red doors, marking them out from other residents in Middlesbrough.

An inquest into the death of a prison inmate in Wales found his epilepsy had not been diagnosed because G4S jail staff failed to take him for medical appointments and did not convey necessary information to a health consultant.

G4S also bungled a security contract for the London 2012 Olympics, failing to provide the specified number of staff. The government deployed members of the armed forces instead.

Now the company is set to take on the running of the cross-border Equality Advisory Support Service (EASS) next month. The helpline aids victims of discrimination on the grounds of gender, age, religion, race, disability and other factors.

Now civil rights group Liberty and 40 other organisations have written to Human Rights Joint Committee chair Harriet Harman – as well as the chairs of the Women and Equalities Select Committee, the Public Accounts Committee and the Home Affairs Select Committee – calling for the contact to be placed on hold.

The letter also calls for an urgent investigation into the tendering process, claiming it was “seriously flawed”.

The letter states: “At a time when reports of hate crime in the UK have surged and the recent EHRC reports have highlighted entrenched discrimination in British society, we can ill-afford G4S involvement in the provision of discrimination advice.”

Until October 2012 the advice line was run by the Equality and Human Rights Commission and in March this year a parliamentary report recommended the service be returned to that organisation.

Liberty has also produced a dossier collating the company’s reported failings on human rights and equality in the UK, which includes allegations that a 15-year-old was kept in her room at a secure training centre overnight after miscarrying, only receiving hospital treatment a week and a half later.

It also includes claims from G4S whistleblowers that unsafe restraint techniques have been used by staff.

Bella Sankey, director of policy at Liberty, said: “The EASS provides expert advice to those who face discrimination – whether refused accommodation because of their race or sacked from their job because of their age.

“G4S has been responsible for countless human rights violations, and the mistreatment and even unlawful killing of people in their care. It’s hard to think of a company more ill-equipped to provide this vital service.

“Liberty joins other equality and rights organisations in demanding that this perverse decision be halted while parliament investigates.”

The letter, also signed by groups including Operation Black Vote, the Legal Aid Practitioners Group and the Howard League for Penal Reform, expresses “profound concern” over the awarding of the contract, which will run for three years from October 1, with the option of a two-year extension.

It states that G4S “has earned a reputation for serious, systematic mismanagement and discrimination”, adding: “It has been responsible for serious human rights violations against those within its care, including at youth detention centres, adult prisons, immigration centres and during removals.

“We suggest that [G4S] is manifestly ill-equipped to provide advice on discrimination and human rights," it said. "We suggest that members of the public are unlikely to have confidence in an advice service operated by G4S.”

Neil Malpas of G4S said: “We would welcome and support any review of the tendering process for the EASS helpline, which in our view was conducted very openly, professionally and competitively.

“We were awarded the contract on the strength of our work handling other complex call centres including the Department of Work and Pensions’ child maintenance options service. We have supported that helpline for separating parents over the past three years and feedback from callers and the DWP has been positive. We will bring that experience to the Equality Office’s advisory service and ensure that our team has the knowledge, skills and training to provide clear, supportive and practical advice to people who turn to this helpline when they are concerned they have been discriminated against.”

The Equalities Office, headed by Justine Greening, did not respond to calls for comment.