The document, seen by the BBC, is the most detailed draft with a 20-point plan on workers' rights alone.
It was yet to be signed off by most senior party figures, including the shadow cabinet and Labour's national executive committee.
The final version will form the foundation of Labour's bid to win over voters in the June 8 general election.
The detailed document has been branded as "socialist" and filled with "class envy" by many sections of the British media as it proposes nationalisation of the country's railways and the postal service and having at least one state-owned electricity supplier.
"We do not comment on leaks. We will announce our policies in our manifesto, which is our plan to transform Britain for the many, not the few," a spokesperson for Labour leader Jeremy Corbyn said.
The ruling Conservative party termed the draft as a sign of the chaos that a Labour led government would unleash on the UK if it were to win the general election.
"This is a total shambles. Jeremy Corbyn's plans to unleash chaos on Britain have been revealed.
"The commitments in this dossier will rack up tens of billions of extra borrowing for our families and will put Brexit negotiations at risk. Jobs will be lost, families will be hit and our economic security damaged for a generation if Jeremy Corbyn and the coalition of chaos are ever let anywhere near the keys to Downing Street," a Conservative party spokesperson said.
Other details of the manifesto include abolishing tuition fees for students at university, spending an extra 8 billion pounds on social care and not making "false promises" on immigration.
(This story has not been edited by NDTV staff and is auto-generated from a syndicated feed.)