Grenfell Tower survivors have demanded justice for their loved ones in a highly charged meeting at parliament in which one bereaved resident told the communities secretary, Sajid Javid, that his mother and sister were “murdered and cremated”.

A packed committee room at the House of Commons heard emotional testimony from four bereaved residents including Ahmed Elgwahry who said he had not received an apology from the Royal Borough of Kensington and Chelsea (RBKC) for the fire.

The meeting was called to mark six months since the fire which claimed 71 lives and was organised by Grenfell United, which represents the majority of the surviving residents of the tower and the bereaved. It was attended by the shadow chancellor, John McDonnell, the Liberal Democrat leader, Vince Cable,and the shadow housing minister, John Healey.

“My mum and my sister were poisoned by the smoke, they were burned and they were cremated,” Elgwahry said. “I had to listen to them suffer. I had to listen to them die. I had to watch the flat burn for a couple of days. If that is not torture, I don’t know what is.”

His sister Mariem, 27, and mother Eslah, 64, both died. Eslah was found on the 23rd floor and was identified by her dental records, an inquest heard.

Following their deaths, Elgwahry said he had hoped to see his loved ones but “what I got was fragments of bone and muscle tissue”.

He said the fire happened because “of a culture of negligence and self-interest” and “treating residents as second-class citizens”.

“I asked for one single thing from RBKC and that’s a simple apology,” he said. “I am still waiting. I have received an apology for the aftermath, but not what happened up to the inferno.”

Replying, Javid said: “I am deeply sorry for the failure of the state to be there for the people of north Kensington when they needed it most. In 21st-century Britain, people were left without their homes, their belongings and without any kind of meaningful help. There is absolutely no excuse for that.”

He said he had personally been “frustrated at the pace of help and support” available to residents and the bereaved and that he recognised residents of Grenfell had been “pushed to the very edge of consciousness by society that hoped to forget about them”.

Referring to the efforts of Grenfell United, which has been lobbying for greater representation for the community on the public inquiry which entered its second day on Tuesday, he said: “You have shown the city, you have shown the world what community is all about.”

Natasha Elcock, 39, told how she was trapped on the 11th floor with her six-year-old daughter and boyfriend. She flooded the bathroom to help protect against the fire and managed to flee after 90 minutes when a fire crew reached her. They stumbled over a body on their way out.

“What went on after that was just unbelievable,” she said. “We want justice for the young children who died in that building and that person who I had to disrespect by stepping on. Grenfell should never have happened. We want justice for those 71 people that died [so they] have not died in vain.”

Bellal El Guenuni, told how his pregnant wife and three children escaped at 3.30am but his son and daughter collapsed and went into a coma. He described how the rest of his family were in hospitals in other parts of the capital. He was given a room in a hotel, only to be told he couldn’t stay beyond one night and had to look for another place. Then, when his children were discharged, he was told he couldn’t have so many people in one room.

“After the fire, I thought things would be better, but I don’t know if we were ignored or dismissed or they were incapable,” he said. “Even now we are teaching [the officials] how to be human. When the councillors come and speak with us we have to teach them how to talk to us.”

He told the Westminster politicians: “We need you to help us because everybody else has failed. We have no more faith in the local government. We need you to be understanding where we are coming from.”

Capturing the feeling of a stunned and visibly emotional audience, Healey said the group had presented some “very hard truths” and what they had said “forcibly reminds us of how much there is left to do”.