Cleaners, porters and caterers from hospitals joined other low-paid private workers in an East London demonstration for a minimum wage of �6.50 an hour.

Contracted out workers get a raw deal - they are paid less and receive fewer benefits that their public sector counterparts

Sampson Lowe, policy officer, Unison

The East London Communities Organisation (Telco), which organised the march, said that 80% of London's lowest-paid workers were black and worked for the National Health Service.

The march was also aimed at highlighting the pay gap between NHS staff and private contractor workers.

In the past few months, university staff, teachers and council workers have voted to strike over London allowances.

'Unhealthy' pay gap

Many ancillary health service workers, such as cleaners and porters, have seen their wages fall as a consequence of contracting out to the private sector.

According to figures from Unison, the public sector union, cleaners employed directly by the NHS earn as much as 25% more than workers doing the same job, but who are employed by private contractors.

The pay divide

NHS cleaner: �5.43-�5.48 per hour Contracted out cleaner: �4.20-�4.73 NHS porter: �5.43-5.58 Contracted out porter: �4.20-�5.08 Source: Unison

The average wage for a contracted-out hospital cleaner and porter is only a fraction above the national minimum wage, which was increased by 10p to �4.20 on the 1 October.

Sampson Lowe, policy officer for Unison, said: "People on low pay live shorter, unhealthier lives.

"In truth, the tax payer subsidises low paying employers through health and benefit costs."

As for the plight of contracted out workers Mr Lowe was unequivocal.

"Contracted out workers get a raw deal - they are paid less and receive fewer benefits than their public sector counterparts," he told BBC News Online.