More than 200 homes on the Broadwater Farm estate in north London are at risk of catastrophic collapse and all the families are to be urgently moved out following tests carried out in the wake of the Grenfell Tower disaster.

Two residential blocks, which were completed in the early 1970s are among 11 buildings on the Tottenham estate that failed structural tests, are the most seriously affected and are likely to be demolished.

The tests uncovered serious structural failings, which make the homes vulnerable to collapse in the event a gas pipe or gas canister explodes or a vehicle strikes the base of the buildings. Tangmere House, a six-storey block, and Northholt, an 18-storey block, are those worst affected.

The estate was the scene of riots in 1985 and its blocks were built using the same large-panel system used on Ronan Point, where a gas explosion in 1968 caused progressive collapse, killing four people.

The type of tests the buildings failed were initiated following that disaster but the problems at Broadwater Farm were only uncovered in the last 12 months.

“Neither Tangmere nor Northolt can remain occupied long-term as they are in their current structural state,” the London Borough of Haringey said in a report into the problems. “The presence of piped gas in Tangmere continues to pose a health and safety risk to residents. Tangmere failed structural tests, which means there is a risk of progressive collapse from an explosion caused by piped gas or from an explosion from a lower impact event such as a vehicle strike or bottled gas explosion.”

The gas company Cadent has said it must disconnect the gas main in October which means the rehousing must be started now.

Some residents reacted with anger to the news as they faced the prospect of being thrown out of homes they have lived in for decades.

“It’s disgusting and it is very stressful,” said one woman who has lived in the same flat in Tangmere for 38 years. “Ain’t it funny this has just come out after Grenfell?”

She had just come from the housing office, and said: “They said they will find us a place to stay and you will have to take it. That’s wrong.”

Nicky Erar, 46, a mother of two, said: “These blocks must have been dangerous for many years. It is quite scary that it is not safe. We worry about it at night.”

A mother in the same block said: “We don’t know where they are going to rehouse us. But at least they are moving us. Who wants what happened in Grenfell to happen to their loved ones? ”

Other residents reacted sceptically to the council’s claim that new council houses will be built voicing fears the site might be sold off to private developers, although there is no evidence that is the case.

The council said: “There will be a consultation but the council’s preferred option is to demolish the blocks and replace them with high quality, new council homes built on the estate.”

It said it wants to start to re-house residents of Tangmere “now, so that there is sufficient time to rehouse residents before the end-of-October deadline”.

The council has estimated that it will cost around £28m to strengthen the two buildings so it prefers to demolish them.

The council’s housing arm, Homes for Haringey, is undertaking home visits to every property in both blocks to check for the presence of both bottled gas and oxygen cylinders. Concierges are stationed on the doors to flats 24 hours a day to prevent residents bringing in such items.

In a letter to residents the landlord said: “We understand that moving will cause you disruption; which is why we are committed to working closely with you to find a home permanently or temporarily that suits your needs.”

Not everyone was upset to be leaving. Barry, 17, who has lived with his family in the estate for seven years, said: “I am happy to leave if they give us a new house in a better area. This is where the 2011 riots started. It is in a bad state. No one cares about this place.”

Emina Ibrahim, Haringey’s cabinet member responsible for housing, said: “We understand that residents on Broadwater Farm – particularly those in Tangmere and Northolt blocks – will have questions and concerns. We are committed to providing a safe, decent and affordable home for everyone and I want to assure all affected residents that we will carefully consider all of the issues, and that any decision we take will be with primary consideration for the safety, aspirations and rights of our tenants.

“A decision on the long-term future of these blocks will only be taken following proper consultation with residents. Our residents are our absolute priority and I would encourage anyone with questions to contact the dedicated Homes for Haringey team that has been set up on the estate.”

Nine other blocks on the estate with piped gas failed tests at a higher threshold in December, so gas cookers have been replaced with electric cookers in all those 725 flats and gas interrupter valves have been installed which will switch off the gas if a leak is detected.