Tube staff are being attacked and threatened by angry passengers because of "misinformation" about delays to London Underground services, their union has claimed.

The Rail Maritime and Transport union said passengers were being told there was a good service when there were "severe delays". London Underground denied the claims.

The union also alleged that major delays were being described as "minor" and that messages to passengers were changed too quickly after an incident.

The issue was sparking threats and assaults against staff by frustrated passengers caught up in travel "chaos", said the union.

General secretary Bob Crow said: "Abuse of service information to create a misleading picture as to what is running and what isn't immediately throws our members on the stations and platforms into a confrontational situation as angry passengers realise they have been misled.

"We are calling for an end to this practice. You cannot cover up the impact of cuts to jobs and finances by throwing up a barrage of misinformation. It might suit the politicians and the senior managers but it's frontline staff who are left to take the flak at station level."

Howard Collins, chief operating officer at London Underground, said: "London Underground provides timely and accurate real-time information on how Tube services are operating for the benefit of our customers and staff. This is provided directly by Transport for London through tfl.gov.uk, and on the network, through 'rainbow' boards and customer announcements. Also, via the many real-time travel apps created by developers using our trusted real-time data.

"It is completely wrong to suggest we provide misleading or inaccurate information, or that there is any evidence this is leading to violence against Tube staff.

"We know this real-time information is valued by our customers and we have recently improved it to make it more detailed and relevant to our customers. For example, if there is good service on one branch of a line but minor delays on another, we can now show that."

Meanwhile, there were severe rush-hour delays on the Underground's Jubilee line due to a signal failure at North Greenwich in south London.