The former St Helens and Great Britain scrum half joined the capital club earlier this year, after their off-field issues were resolved by a move to The Hive, home of Barnet football club.
However, speculation over his position mounted when he was spotted at Salford’s game with Wakefield on Sunday, when London were playing against Widnes at the same time.
Long tweeted: “London Broncos wanted to change my contract to part time. Finding that very hard with the travel. Wish the boys good luck for the rest of the year.”
London were Long’s fourth club in less than a year. He resigned as assistant coach at Salford after 18 monts in April, and then had a three-month spell at Wigan.
He ended the season as football manager at Featherstone, acting as a stop gap before the arrival of John Bastian as head coach at the Bigfellas Stadium, and helped the Samoa national side at the recent World Cup.
Long retired from playing back in August 2011, after two injury-hit years at Hull.