Mohammed Fouad’s eyes darted from place to place on the quiet Gaza City street. Puffing nervously on a cigarette, he began brisk strokes with an aerosol paint can and in just five minutes completed a near-perfect portrait of the late Fatah leader Yasser Arafat.

“If they see me, I’ll go to jail,” Mr Fouad said, referring to the Hamas policemen who forbade him from writing or drawing any pro-Fatah graffiti on Gaza’s walls. “I’ve been to jail five times since the Hamas takeover because of my art.”

Mr Fouad is just one of the soldiers in the graffiti war that currently plays out between Hamas and Fatah on the streets of this contentious coastal enclave.

Each movement maintains its own graffiti arm, with artists hand-picked by faction leaders and given professional training before they are sent out to paint Gaza’s walls.

Orders of what to write and where to write it come straight from the top and, as a result, Gaza’s already cramped streets are stained with layer upon layer of aggressive political calligraphy, portraits of the slain and depictions of militants’ battles with Israeli soldiers.

“Fatah in the West Bank, wait for us,” read one scrawl in the central Gaza Strip town of Khan Younis, a reference to the 2007 civil war between Hamas and Fatah that routed the latter from the Gaza Strip and left them in sole control of the West Bank.

“Hamas is willing to sacrifice its leaders before the people,” read another, a pro-Hamas piece in the northern refugee camp of Jabaliya.

The two factions have been bitter rivals since the war of 2007. With Hamas in control of Gaza and Fatah of the West Bank, each Palestinian territory has been marred by clampdowns, arrests and reports of torture by both sides.

Now there is little room for political dissent in either territory, even when it comes by way of spray paint.

Fatah artists have said they are kept under tight watch in Gaza, where Hamas rules, and routinely threatened with imprisonment if they dare take their political affiliations to the street.

Even drawing Arafat, or the portraits of other late Fatah leaders, Fatah artists have said, is considered a crime.

But Gaza’s political graffiti culture came long before the recent Hamas-Fatah rivalry – and has been an integral part of territory’s recent history.

Unlike the emphasis on individual artists found in western graffiti, political street art in the Gaza Strip is very much a community affair, developed as a tool of resistance against Israeli occupation during the Palestinian intifadas of 1987 and 2000.

Without access to the internet or other forms of mass communication, Gazans turned every wall into a veritable news bulletin as a way to fight back.

Organisations used graffiti to announce strikes and demonstrations, or even taunt Israeli soldiers with pro-Palestinian messages and claims of responsibility for attacks carried out the night before.

The endless stories of war, occupation, tragedy and resistance were recorded on Gaza’s walls.

But now, for the people of Gaza, the war of political graffiti is between themselves.

“It was easier with the Israelis because we knew who our enemy was,” said Alaa Abdul Majid, 30, Fatah’s premier graffiti artist in the Gaza Strip.

He said that several days before the November 11 anniversary of Arafat’s death, Hamas phoned him and warned him against celebrating the late Fatah leader through graffiti. A Hamas police spokesman, Islam Shahwan, would not comment on whether or not his police force arrests artists for painting pro-Fatah street art.

“I paint for my homeland, and for all martyrs with the symbols of Palestine,” Mr Majid said. “So why is Hamas stopping me? We are all Palestinians.”

But Fatah itself, when it controlled the Gaza Strip under the Palestinian Authority, often removed pro-Hamas art or arrested the movement’s graffiti artists under the guise of a clean-up campaign.

It was not always like this.

Before the Hamas takeover of Gaza, artists from both factions would often work together, writing joint pieces and even offering graffiti condolences for the death of members of the opposite faction. In fact, most of Gaza’s graffiti artists, whether Hamas and Fatah, are friends.

Politics would not get in the way of their competitive camaraderie, they said, even if they are forbidden from writing together like they used to.

“The best Hamas artist in Gaza, he is my good friend,” said Mr Majid, referring to a man named Abu Mohamed who owns an art shop in Gaza City and was hired by Hamas a decade ago to spread their political messages.

“He called me yesterday when he was writing a piece to get my advice, and I helped him.”

It is such things, the nuances of the political infighting in the Gaza Strip, said the psychiatrist Eyad Sarraj, that are important – and are not always apparent when observing the territory’s marked-up streets.

“The graffiti in Gaza doesn’t always reflect the thoughtful conversations going on behind closed doors, it presents things as black and white,” Mr Sarraj said. “But graffiti, you know, is its own battlefield.”