A released Israeli hostage whose husband is still being held by Hamas in Gaza has told the BBC she is “screaming” for him to be freed and has called on international mediators to do more.

Aviva Siegel was released in November after being held for 51 days. Her husband Keith has now been a hostage for 193 days.

The Siegels were kidnapped from Kibbutz Kfar Aza on 7 October when Hamas attacked Israeli communities near Gaza, killing about 1,200 people and taking 250 hostages.

Israel’s retaliatory campaign in Gaza has killed more than 33,000 Palestinians, the Hamas-run health ministry there says.

Aviva never imagined that nearly five months after she said goodbye to her husband in Gaza, he would still be held captive there enduring brutal conditions.

“I’m not speaking. I’m screaming and need help from the whole world to help take Keith out and all the hostages,” she said.

“I was there for 51 days. I know what it’s like and when I try and imagine Keith being thrown into the corner, on a mattress on the floor, with no human rights at all. It breaks my heart, and he’s not there for a day and not for two days. I’m back for nearly five months,” she said.

In her first interview with a British media outlet, the 62-year-old spoke not knowing if Keith, an American-Israeli grandfather, was still alive.

“It’s terrible. I’m broken up into pieces. It’s very hard to handle the situation to think about them being there, to see what I saw, going through what I went through with terrorists that were so mean to us, and so brutal, and that Keith is still there.

“We don’t know anything about him. We don’t even know that he’s alive. And it’s difficult for me to think that he’s alone with the terrorists.”

Hamas attackers broke into Aviva and Keith’s home and dragged them away, breaking Keith’s ribs and shooting him in the hand. Once in Gaza, the couple were moved from place to place 13 times.

“One of the times they took us down to a tunnel and there was no oxygen there. And they just left us there. And I can’t explain what the feeling was.

“Not being able to breathe and you know that it might be your last hours. There was just no oxygen so they just left us. They went up to the ground to the fresh air and they just left us… we felt like we kind of died.”

At other times they stayed in houses, kept with little food in the dark and ordered not to stand or talk for days.

Aviva is clear that some of the female hostages she was held with were sexually assaulted by the Hamas men holding them.

“I was there and I saw the girls coming after those things happened and telling us what happened… One of the days one of the girls went to the toilet, and when she came back, I could see on her face that something happened and I got up and I gave her a hug and the terrorist came in and started screaming.

“After a couple of hours she came and she told us she said ‘he touched me’ and that was one of the terrible moments because I felt that I couldn’t even look after this little girl. She’s just a child. She could be my child. And the only thing I could was look at her in the eyes because we weren’t allowed to hug, we cried inside.”

On another occasion one of the gunmen badly beat a female hostage, Aviva said.

“He pulled up her hair and pushed her on the floor. She fell with the gun [pointing] into her face and he said ‘one more word and I’m going to kill you’.”

Even though she put her fingers in her ears Aviva could still hear the hostage being hit.

On the 50th day the Hamas gunmen told her she was being released; she begged them not to leave her husband behind.

“They didn’t even let me go and say goodbye to Keith until I pushed them. I said ‘I’m going to say goodbye’. I told him to be strong for me and I’ll be strong for him. And I’m happy that I did that because I’m sure that he thinks about that sentence.”

Throughout her captivity Aviva believed her son Shai had been killed when Hamas stormed the kibbutz.

“On the bus on the way back, I told the social worker that I think I’m going to faint because they’re going to tell me that Shai died. And she came back after 10 minutes and told me you have four children. And I was just the happiest person.”

Keith still doesn’t know that Shai survived.

Aviva is distraught that her husband and the other hostages haven’t been released and believes Hamas is “getting the pleasure of them being there and seeing us suffer”.

“They feel like they’ve won. They are playing games.”

She wants international mediators including the US, Qatar and Egypt to do more.

“I think that Qatar needs to understand they need to be much stronger to help to get them out. And if they do, I think it will be the best thing for them because people in the whole world will look at them as strong and the US needs to stand strong and help because we need help… I think that everybody the whole world needs to do more.”

On Wednesday, Qatari PM Sheikh Mohammed bin Abdulrahman Al Thani said long-running talks for a truce and the release of hostages were “going through a sensitive stage with some stalling, and we are trying as much as possible to address this stalling” without giving more details.

The US says Hamas rejected the latest proposal put to it, which included an initial six-week ceasefire that would see the group release 40 hostages who are alive, with the priority being given to female captives including soldiers, men over the age of 50 and those with serious medical conditions.

The deal “would achieve much of what Hamas claims it wants to achieve”, said US state department spokesman Matthew Miller.

But Hamas reportedly told negotiators it was not holding 40 hostages in this category. Israeli officials had previously said they believed about 133 hostages were still in Gaza with more than 30 of them presumed dead.

Hamas also wants a permanent ceasefire, the complete withdrawal of Israeli troops and the return of displaced Palestinians to northern Gaza without restrictions. Prime Minister Benjamin Netanyahu meanwhile has insisted that Israel will continue fighting until Hamas is destroyed.

Aviva is only too aware that as talk drag on without agreement, more of the hostages may already be dead.

“I’m starting to lose my hope. And I’m sure that Keith is too. When I was there I used to think to myself I’d rather be dead than what I’m going through and I’m sure Keith thinks that too.”