The band are due to play Radio 1's Big Weekend in Swindon
Singer Tulisa Contostavlos, from pop group N-Dubz, has been told she is not suffering from swine flu, a spokesman has confirmed.
The 20-year-old, from north London, was taken to hospital in Athens last week after falling ill on board a flight.
Her spokesman said tests for swine flu were negative, but she had been kept in "isolation" until Tuesday just in case.
The band are expected to play Radio 1's Big Weekend on Sunday, but it is not clear whether Contostavlos will appear.
"Hopefully she'll get better and be able to fly back towards the end of the week, but we don't know if she will be well enough," her spokesman said.
The singer was diagnosed with flu on Tuesday, but was released from hospital on Saturday and has been staying with her aunt in Greece.
Doctors told her not to leave the house until they were certain she was not suffering from swine flu.
The three-piece, which includes Miss Contostavlos's 21-year old cousin Dino 'Dappy' Contostavlos and their childhood friend Richard Rawson, 22, have enjoyed huge success this year.
They currently occupy the top spot in the singles chart, featuring on Tinchy Stryder's hit, Number 1.