The Roman Catholic Bishop of Brentwood, Thomas McMahon, has strongly criticised the Government's failure to regularise undocumented migrants living in Britain.

Bishop McMahon made his comments in his homily at the 'Mass in Support of Migrants Workers in London' at Westminster Cathedral on Monday, the feast of St Joseph the Worker.

The bishop emphasised the importance of welcoming migrants. "Welcoming and hospitality have always been at the very heart of the Bible and have been very much the tradition of the United Kingdom. Migrants helped to rebuild the United Kingdom following World War II and are continuing to regenerate London and this country. They make an indispensable contribution."

In his homily, Bishop McMahon drew attention to efforts being made in recent years to extend this welcome to the many long-term undocumented migrants in the UK.

According to migrant experts, these migrant workers have lived and worked in London for many years, often paying taxes and contributing to the economy and society. Their status in the UK, however, is that of being here illegally, and many are threatened with deportation.

Bishop McMahon said: "We are concerned here today with the plight of the long-term migrants and the Government's failure to respond must be consistently challenged.

"For any government to choose to do nothing about regularisation is irresponsible and leaves thousands of migrants open to exploitation and fear. I can only describe it as shameful and unjust."

The Mass for Migrants Workers in London was attended by over 2,000 people from more than 40 countries. The Mass was celebrated by Cardinal Cormac Murphy-O'Connor, Bishop Pat Lynch, auxiliary Bishop of Southwark and Bishop Thomas McMahon.

Also present at the Mass was the Papal Nuncio, Archbishop Faustino Sainz Munoz and civic dignitaries included the Lord Mayor of Westminster. Over 50 priests took part in the celebration of the Mass, many from the 47 ethnic chaplaincies in London.

Earlier in 2008, the Catholic Bishops' Conference of England and Wales issued a new statement about the Mission of the Church to Migrants.

Bishop Lynch said at the time: "Over the last few years, there has been a transformation of the social character of the dioceses in England and Wales.

"Across the country in all our dioceses, we have migrants from nearly every continent in the world, adding people and vibrancy to our parishes.

"We, the Bishops of England and Wales, have been considering this new social reality with a view to issuing a statement calling for a more visible culture of welcome, hospitality and solidarity with our migrant sisters and brothers in God's family.

"We recognise and celebrate their rich cultural and spiritual patrimony and the ways in which they are enriching us as they join us in our parishes and dioceses."

Listen to the bishop's homily in full at www.rcdow.org.uk/multimedia