US Attorney General Janet Reno has upheld a decision by the immigration service giving custody of six-year-old Elian Gonzales to his father in Cuba.

But Ms Reno's ruling lifted a Friday deadline for the return of Elian, which means the boy will remain in Miami for the time being.

The attorney general acted after a Florida judge granted temporary custody on Monday to the shipwrecked boy's Miami-based great uncle, ruling that he should stay in the US until a hearing about his future on 6 March.

Ms Reno said the question of who spoke for the child in applying for admission or asylum was a matter for the federal immigration law.

She added that the state court ruling had "no force or effect" on the Immigration and Naturalization Service's (INS) decision in the case.

"Based on all the information we have to date, I see no basis for reversing," said Ms Reno.

However, she lifted the INS deadline of 14 January for the boy to be returned to his father, Juan Miguel Gonzalez, and pointed the way for further litigation by saying legal challenges should come in a federal court.

The attorney general also appealed for a quick resolution to the case: "It is my strong hope that we can work together to resolve this child's status as soon as possible."

Political ties

Questions were earlier raised about the impartiality of Florida Judge Rosa Rodriguez, whose ruling on Monday awarding temporary custody of Elian to his great uncle, Lazaro Gonzalez, was widely welcomed by Miami-based Cuban exiles.

Several leading legal commentators said there had to be serious doubts after her ties to a political consultant, Armando Gutierrez, were disclosed.

Mr Gutierrez is the spokesman for the Miami relatives who have been caring for Elian.

During her 1998 campaign to be elected a circuit judge, Ms Rodriguez paid Mr Gutierrez and his wife more than $63,000 for advertising and political consultancy services.

In further legal wrangling, lawyers for Elian's great-uncle said they planned to refile a petition seeking political asylum for the boy. An initial petition was withdrawn last week after the INS ruling.

The INS is also studying a subpoena issued by Republican congressman Dan Burton, which orders Elian to appear before his committee in Washington in February.

Cuba protests

Elian was found clinging to an inner tube off the coast of Florida on 25 November, after his mother, stepfather and nine other would-be illegal immigrants drowned fleeing Cuba.

Since then he has been the centre of intensive legal wrangling between the US authorities, Cuban exile leaders in Florida and the Cuban Government.

There have been several large demonstrations in Havana in support of Elian's father - the latest on Monday night prompted by Judge Rodriguez' ruling.

The protests are expected to continue, with the official Cuban daily, Granma , announcing an unprecedented march of 100,000 Cuban mothers on Friday morning.