Their faces covered with black balaclavas, AK-47s in hand, militants from Hamas's armed wing have become a familiar presence in the Gaza Strip -- and for many that remains a key problem.

Hamas, the Islamist movement that has run the Gaza Strip for a decade, has been seeking to end its long feud with Palestinian president Mahmud Abbas's Fatah, but its powerful armed wing may prove to be a dealbreaker.

The Palestinian Authority is due to take control of Gaza by Friday under a reconciliation agreement signed in October, but Hamas is flatly refusing to disarm.

Security control could derail the long-awaited accord, with Abbas warning he will not accept a situation akin to Hezbollah in Lebanon, where the Shiite group's militia wields major power.

"The weapons of the resistance are a red line that is non-debatable," Khalil al-Hayya, deputy head of Hamas in Gaza, said at a press conference on Monday.

"These weapons will be moved to the West Bank to fight the (Israeli) occupation. It is our right to resist the occupation until it ends."

The size and strength of Hamas's armed wing, the Ezzedine al-Qassam Brigades, has been a source of speculation.

Hamas, which seized control of Gaza in 2007 in a near civil war with Fatah, does not comment on such details.

Al-Qassam membership has been estimated at 20,000-25,000 -- roughly the size of the Czech Republic's active military personnel, according to figures cited by the World Bank.

Before a devastating 2014 war with Israel, militant groups in Gaza were believed to have a total of some 10,000 rockets, including 6,000 for Hamas, an Israeli military analysis at the time said.

- 'With flowers, with roses' -

Most were short- and medium-range rockets with a range of between 20 and 45 kilometres (about 12 to 28 miles), the analysis said.

But there were also a number of longer-range rockets that could reach up to 200 kilometres, it said.

It is thought that around half to two-thirds of the rockets were fired during the war, said Neri Zilber of the Washington Institute for Near East Policy, who often writes on defence issues.

Zilber said it is believed that rocket arsenals in Gaza have since been rebuilt to around 10,000 -- though with a greater focus on shorter-range weapons since they are more difficult for Israel's missile-defence system to shoot down.

Beyond those and small arms, militants in the Gaza Strip are thought to have other weapons including rocket-propelled grenades, he said.

Many were likely smuggled through tunnels.

In August, Hamas's leader in Gaza Yahya Sinwar said newly improved relations with Iran had made it the "biggest supporter" of Hamas's military wing.

The weapons are key to Hamas's ideology, with officials from the group, labelled a terrorist organisation by the United States and the European Union, saying they are needed for defence against Israel.

It does not recognise Israel -- unlike the Abbas-led Palestine Liberation Organisation -- and has fought three wars against it since taking power in the Gaza Strip.

"When Israel occupied Palestine, Israel did not come with flowers, with roses," said Gaza-based academic Asad Abu Shark.

"We have to have arms in order to defend."

Israel says that Hamas is determined to attack it, and in October its forces blew up a tunnel stretching from Gaza into its territory, resulting in the deaths of 12 Palestinian militants.

Such tunnels have been previously used for attacks.

- 'Division will remain' -

But Hamas's armed resistance has recently run up against other pressures in the Palestinian enclave of some two million people.

Under an Israeli blockade for more than a decade and with its border with Egypt kept largely closed in recent years, Gaza has seen worsening humanitarian conditions.

Abbas has piled further pressure with punitive measures against Hamas, including cutting electricity payments, worsening an already severe power shortage.

Hamas has sought help from Cairo -- hoping to have the Rafah border with Egypt opened -- and has faced pressure to pursue reconciliation in return.

A deal mediated by Egypt was signed on October 12, though it lacks details on security control.

A first deadline was met, with Hamas handing over Gaza's borders to the Palestinian Authority on November 1.

The next, more important deadline comes on December 1, when Hamas is supposed to give up its decade-long dominance of Gaza and hand power to the PA.

But there are doubts over what kind of transfer will occur and whether it will be mainly symbolic.

Ghassan Khatib, a former PA minister, said basic differences between Fatah and Hamas on how to pursue the Palestinian cause -- diplomatically or through armed resistance -- would prevent reconciliation unless overcome.

"So long as we have these differences, the division will remain," he said.

Source:AFP