Illegal immigrants on loose in Sydney

Three Chinese nationals have escaped from a Detention Centre in Sydney's west.

The escapees left the Villawood unit in the early hours of this morning, a spokesman told AAP.

They were not part of a group of 89 failed asylum seekers transferred to the centre from Christmas Island at the weekend, the Department of Immigration said in a statement.

The department has also confirmed another four detainees had escaped from the centre in the past month.

No further details of the escape were currently available. However, the department expects to update the media later today.

Macquarie Radio Network reported the Chinese nationals were long-term detainees and escaped between 5am and 8am.

Villawood Detention Centre is used to detain asylum seekers and people in violation of visas.

British security firm Serco, which manages Villawood, sacked 10 guards after the first four escapes, News Ltd reported.

Of these earlier escapes, Serco said one detainee got out by strapping himself to the bottom of a truck carrying building supplies and a Ghanaian man went free after being let outside to pray at a nearby church.

A group of 89 Iraqis, Sri Lankans, Afghans and Iranians was transferred to Villawood from the Christmas Island detention facility on Saturday after they were found not to be refugees.

The transfer has been criticised by opposition immigration spokesman Scott Morrison, who says it could open new legal avenues for the asylum seekers that could delay or prevent their deportation.

A spokeswoman for security firm Serco, which runs Villawood Immigration Detention Centre, declined to comment on the escapes.

She referred AAP to the Department of Immigration for any additional comment on the issue.

Serco signed a contract with the Department of Immigration in 2009 to run Villawood and four other Australian immigration detention centres, according to its website.

It also operates long and short-term immigration residential housing and national and international transport services for the government.

- AAP