Amir al Sharif is keen to talk. For nearly two hours he does so almost non-stop, opining that Hamas was originally supported by Israel’s Shin Bet security service to challenge the PLO and Fatah. He said since then the Islamist movement had never missed an opportunity to weaken Fatah and complained that since Hamas had agreed to a ceasefire with the “Zionist enemy”, it was acting as “Israel’s policeman” in the Gaza Strip.

A few years ago, almost the exact same rhetoric would have been heard from a Hamas leader in hiding. But the tables have turned in the Gaza Strip, and where Islamist militants once were on the run from both the direct rulers of Gaza – in the shape of Fatah and the Palestinian Authority – as well as the Israeli army, it is now Fatah militants.

And with ordinary Gazans yet to feel any tangible change in their daily lives as a result of the Gaza ceasefire, opposition to an otherwise broadly supported ceasefire may grow.

Mr Sharif, 34, is the leader of the Aqsa Martyrs’ Brigades, a militant group affiliated to Fatah, in the Gaza Strip. In the wake of the Gaza ceasefire, the Brigades fired rockets across the border almost wrecking the hard-wrought Egyptian-mediated agreement. Mr Sharif is now wanted by Hamas.

“We have our reservations over the ceasefire agreement, not least because it was imposed by Hamas without consultation,” said Mr Sharif on Tuesday night at the home of a friend in the Jabaliya refugee camp in Gaza City. “We reserve the right to retaliate against Israeli violations of the ceasefire both here and in the West Bank.”

That position, as Mr Sharif is well aware, has brought the Aqsa Martyrs’ Brigades in Gaza into conflict not only with Hamas but also the position of Mahmoud Abbas, the president of the Palestinian Authority and leader of Fatah.

“Abu Mazen [Mr Abbas] ordered all factions to respect the ceasefire,” Mr Sharif said. “We respect Abu Mazen, and we are prepared to respect the ceasefire. But Abu Mazen’s orders are not verses of the Quran. If we feel that it is in the national interest, we will respond to Israeli crimes.”

Hamas spokesmen are acutely aware of observations that Hamas is acting in a way that it criticised the Palestinian Authority for on a number of occasions and vehemently reject suggestions that Hamas enforced the agreement over the wishes of other factions.

“The ceasefire agreement came as a result of factional consensus,” said Ihab Ghusain, a spokesman for the Hamas interior ministry. “It is not imposed by Hamas, and it does not mean the resistance is over. Just because there is a ceasefire does not mean that we are not still under occupation.”

Mr Ghusain was reluctant to characterise Hamas’s actions against rockets fired by other factions as a clampdown, describing instead the detention of seven members of Islamic Jihad and the Aqsa Martyrs’ Brigades as “routine investigations”.

He did not deny that Hamas would act to prevent rocket fire in the future but added that Hamas and Islamic Jihad had set up a “crisis management group” to discuss possible future incidents.

“The ceasefire came about as a result of consensus. Any response to Israeli violations should also be agreed upon by the factions,” Mr Ghusain said.

As for Fatah and the Aqsa Martyrs’ Brigades, Mr Ghusain said Mr Abbas had made clear the position of Fatah and that those who acted against Mr Abbas’s wishes could not therefore properly be considered members of the faction.

“We know there are elements close to [erstwhile Gaza strongman Mohammed] Dahlan who want to see the ceasefire fail because they are acting against the interests of the Palestinian people,” Mr Ghusain said.

Nevertheless, he said, the real key to the ceasefire’s longevity lay in Israel’s intentions. By and large, Gaza has been quiet since the ceasefire started nearly a month ago, but ordinary Gazans have yet to reap the benefits.

Hamada al Bayari, of the UN Office for the Co-ordination of Humanitarian Affairs (OCHA), said that while there has been a “significant” reduction in military activities from both the Palestinian and Israeli sides, not much else has changed in the Strip.

“We are always on the brink of disaster in Gaza,” Mr Bayari said. “And until there is an improvement in the access of goods and people, that won’t change.”

OCHA has not noticed any significant change in the kinds of goods coming into Gaza after the ceasefire came into effect.

“The fuel situation is a little better than it was, and there is no shortage of food or medicine, but there is a deficit of all those goods that can help make Gaza function again,” Mr Bayari said.

Gaza’s 1.5 million people still suffer five-hour electricity blackouts every day while construction materials are not coming through, paralysing building projects and industry and making needed infrastructure repair impossible, an especially acute problem with regards to Gaza’s sewage system.

“The whole point of the ceasefire was to break the siege,” said Khalid al Baatch, of Islamic Jihad. “We cannot accept the situation if it continues like it is. So far, we have felt no increase in the number of goods coming through while patients, students and people seeking work or to reunite with their families abroad are still not allowed to leave Gaza.”

Mr Baatch said Islamic Jihad would continue to respect the ceasefire – he called the detentions by Hamas of Islamic Jihad militants who had fired rockets after the ceasefire started a “misunderstanding” – but warned there was a limit to the group’s patience.

That too was the message from Mr Ghusain. Without an opening of the crossings, the ceasefire would not have served any purpose. Neither Mr Ghusain nor Mr Baatch would be drawn into any timetable for when the ceasefire might break down should the situation remain the same.

But in a Gaza turned upside-down by the Hamas takeover a year ago, it was one point of rare agreement with Mr Sharif.

“We know what Israel is like,” he said. “Israel cannot be trusted to keep its commitments. I don’t expect this ceasefire to last long.”