As Israel presses its military offensive across Gaza, the army has been repeatedly advising some two million civilians to move to a "humanitarian zone" smaller than London's Heathrow Airport.

Al-Mawasi is a narrow strip of land by the Mediterranean Sea. It has few buildings and largely consists of sandy dunes and agricultural land.

The zone designated as safe by the Israel Defense Forces (IDF), is just 8.5 sq km (3.3 sq miles).

Reem Abd Rabu has spent the last few weeks sleeping on the ground and sharing a tent with four other families in the area.

She is one of the 1.8 million Palestinians who have been displaced since the war began on 7 October after Hamas's attack on Israel.

She first travelled to Khan Younis after fleeing northern Gaza, but after nearby houses were bombed, she said she felt she had to go to the place the Israeli army identified on the map as safe.

Reem told the BBC al-Mawasi was an abandoned place, "not a place for human beings".

She thought it would be safe from the intense bombardment and fighting, but when she arrived, she found little to no basic services.

"Water comes one day and not for the next 10 days, even in the bathrooms. And it's the same thing for electricity," she told the BBC.

The IDF has urged civilians to move to al-Mawasi on at least 15 occasions on social media, the last on 2 December.

The first mention of the humanitarian zone was on 18 October, when the IDF's Arabic spokesperson posted on X: "The IDF orders Gaza residents to move to the humanitarian zone in the area of al-Mawasi, to which international humanitarian aid will be directed if necessary."

Another post, from 21 October, stated: "If your life and the lives of those you love are important to you, head south of Wadi Gaza. We advise you to arrive at the humanitarian area in Mawasi according to our instructions."

Little to no internet connectivity has made it difficult for people to find safe areas in other parts of Gaza.

However, even the IDF instructions on al-Mawasi have changed several times. Civilians say the changing messaging has made it difficult for them to know exactly where to find safety there too.

Each IDF post has been accompanied by a map pinpointing a small area within al-Mawasi that Gazans should evacuate to.

But different areas in al-Mawasi have been designated as "humanitarian zones" by Israel on different dates.

On 18 October, the IDF designated the humanitarian zone marked in purple below. But three days later, the IDF declared a different area - shown in blue.

Then, on 30 October, the area changed again - to the one marked in green.

Mona al-Astal, who has also fled to al-Mawasi, says she is kept awake all night by the sound of shelling.

She is a doctor who says she was forced to leave Khan Younis after her neighbour's home was bombed.

Mona also describes a lack of water, electricity and supplies in the humanitarian zone. She said she had been forced to buy a tent and other supplies for $300 (£238).

Mona said that she had seen people breaking into a UN agency storehouse because "they were so hungry, they have nothing to eat".

To make matters worse, diseases including lice, chicken pox and intestinal infections have become widespread among children, she says.

"With every day that passes, the danger for us here increases," Mona added.

Mohammed Ghanem fled from an area near al-Shifa hospital in northern Gaza where he said more than 25 strikes occurred next to his house.

He said he came to al-Mawasi because "the Israeli army has been directing people here" but said the area was "neither humane nor safe".

He described seeing Israeli tanks less than a kilometre away and said there had been strikes on an area just 500 metres (1,640ft) from the humanitarian zone.

The BBC has identified at least one area of damage approximately 500m away from the designated area of al-Mawasi since the IDF began directing people there.

The BBC has contacted Israeli forces, but has not received a response.

The IDF does claim that on 6 December Hamas "launched a rocket from a humanitarian zone toward Israel", and released a map with al-Mawasi marked.

The BBC has not been able to independently verify this.

International agencies have been voicing concerns about the viability of humanitarian zones in Gaza when fighting and air strikes extend across so much of the territory.

In mid-November the World Health Organization (WHO) said that the plan for al-Mawasi was "a recipe for disaster".

WHO chief Tedros Adhanom Ghebreyesus said: "Attempting to cram so many people into such a small area with such little infrastructure or services will significantly increase risks to health for people who are already on the brink."

The United Nations also has wider concerns about the plan.

"The situation in Gaza is catastrophic; no one and no place is safe," Andrea de Domenico, the head of the UN Office for the Coordination of Humanitarian Affairs (Ocha) told the BBC.

"Safe zones declared unilaterally cannot protect civilians", he added.