The US Senate has announced a breakthrough agreement on legislation to grant legal residency status to millions of undocumented residents in the United States.

The compromise legislation, if approved by both houses of the US Congress, would allow many undocumented residents to remain in the US but would require millions of others - including all those in the country for less than two years - to leave.

The compromise amendment by Republican senators Chuck Hagel and Mel Martinez would allow undocumented residents to obtain legal status if they meet the following eight requirements:

1. Pass national security and criminal background checks
2. Have resided in the United States for at least five years
3. Have been employed in the United States for at least three of the previous five years
4. Have paid all federal and state taxes
5. Register for military selective service
6. Show sufficient knowledge of the English language and US history and civics
7. Pay a $2,000 fine, in addition to required application fees
8. Work for an additional six years after enactment

Undocumented residents living in the United States for less than five years but more than two years could obtain a temporary work visa under the legislation, but first they must:

1. Submit to visa requirements under current law, including background checks, fees and payment of taxes
2. Exit the country and be fingerprinted and processed at a land port of entry. They would be given priority in applying for "green cards" over future immigrants entering as temporary workers

Undocumented immigrants living in the United States for less than two years would receive no benefits under the legislation and would be required to leave the country.

They would, however, be allowed to apply for a temporary worker visa once back in their country of origin.