CAIRO (Reuters) - A complaint filed by critics of the heavily Islamist assembly writing Egypt's new constitution was referred to a higher court on Tuesday, a move likely to give the body more time to complete its work.

The constitution is central to Egypt's transition from military-backed autocracy to democracy following the overthrow of veteran president Hosni Mubarak in February last year.

A Cairo court hearing a case filed by plaintiffs opposed to the make-up of the 100-person assembly sent the case to the Supreme Constitutional Court, the presiding judge said.

The plaintiffs, many of them opposed to the strong Islamist sway over the assembly, had argued that the way the body had been formed was illegal.

In chaotic scenes at the packed Cairo courtroom, the ruling was met with chants for and against the assembly.

Abdel Moneim Abdel Maqsoud, a lawyer for the Muslim Brotherhood, said it would take at least six months for the constitutional court to hand down a ruling on the 43 complaints that the administrative court had been examining.

(Reporting by Tamim Elyan; Writing by Tom Perry; Editing by Mark Heinrich)