Dr Sentamu called on the prime minister to allow Zimbabweans to work
The Archbishop of York has called on the prime minister to "do the right thing" and give failed Zimbabwean asylum seekers the right to work.
Current rules mean asylum seekers are not allowed to work unless they have been given refugee status.
Dr John Sentamu praised the government for not forcing them to return to Zimbabwe but urged it to let them "live in mercy, justice and love".
He joined politicians and community leaders for a protest at Westminster.
Dr Sentamu led protesters - who were shouting "Restore Zim" - to Parliament Square.
The protest began with a service at St Margaret's, Westminster.
He said he hoped the "rest of the world will wake up too" to the "brutality" of President Robert Mugabe's regime, after the G8 group of industrialised nations said they did not accept that the re-elected government reflected the will of the Zimbabwean people.
I would rather they earned their own money instead of depending on the taxpayers
But while applauding PM Gordon Brown's move to suspend forced deportations, Dr Sentamu said: "Give back to your brothers and sisters their human dignity.
"Show your humanity. Show your statesmanship.
"I know that the government is locked in a moral conundrum. But I believe that you should do the right thing for the right person at the right time."
Dr Sentamu earlier told BBC News: "My view would be that if people are qualified and have got jobs why not give them leave so they can work and continue to keep their skills going."
He added: "I would rather they earned their own money instead of depending on the taxpayers, but with very clear rules that say that 'we will determine when we feel the time is right for you to go back'."
Protesters gather in Parliament Square
Campaigners say between 11,000 and 15,000 Zimbabweans are affected by the government's rule.
The march moved to the nearby Home Office to present a letter, pleading the case of the Zimbabweans, many of whom arrived in the UK between 2000 and 2002.
The letter says: "For many years, therefore, they have been languishing, dependent on handouts, forced to seek charity or to work illegally, instead of being allowed to exercise their human right to work and to contribute to the society of which they are a part."
Allowing the Zimbabweans to work in the UK would be "the best investment the UK can now make in Zimbabwe's future," campaigners wrote.
We are looking to see what we can do to support Zimbabweans in this situation
The letter continued: "Until they are able to return to a Zimbabwe which is democratic and safe, the exiles in the UK should be able to support themselves and their families, to pay taxes and contribute to the economy, nurturing skills which would enable them to be more effective participants in the essential rebuilding of the economy and institutions of Zimbabwe."
Mr Brown said: "They are provided with accommodation and vouchers to ensure that they are not destitute, but we are looking to see what we can do to support Zimbabweans in this situation."
Earlier this month, the Court of Appeal delayed a ruling in the test case of a Zimbabwean doctor, referred to as "HS", who is fighting deportation.
No decision will be made before the outcome of a related immigration application before the House of Lords.
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