Hamas has elected a hardliner from its armed wing as its next leader in the Gaza Strip, escalating fears that Israel and the group may be heading towards yet another round of deadly confrontation.

Yahya Sinwar, a 55-year-old who rejects any reconciliation with Israel, was released after 22 years in an Israeli jail in 2011 as part of a prisoner swap for the captured Israeli soldier Gilad Shalit. He will now take over from prime minister Ismail Haniyeh, who is a candidate for the leadership of the Islamist group’s entire organisation.

Haniyeh has served as the prime minister of the Hamas government in Gaza since its takeover in 2007.

The disclosure of Sinwar’s elevation to the head of the group in Gaza comes amid signs of heightened tensions on both sides of the Gaza border . Israel hit a number of Hamas targets a week ago in response to a rocket fired out of the strip. No group claimed responsibility for the rocket but since the Gaza war in 2014 Salafist groups have fired projectiles at Israel on a number of occasions.

A sense of the growing tension was supplied a day after the Israeli strikes by far right Israeli education minister, who said it was a “question of time, not a question of if” when the next round of fighting between Hamas and Israel would take place.

The election of Sinwar would appear to bring to an end a long-running internal struggle in Hamas between the group’s armed and political wings, amid growing dissatisfaction in Gaza towards the group.

Sinwar’s election also appears to have resolved a geographical conflict between “Gazans” such as Sinwar and “those who live abroad”, represented by the likes of Khaled Meshal, the current supreme leader of Hamas, who lives in exile.

Sinwar’s outlook, say analysts, is far more narrowly focused on Gaza than Meshal’s or other members of the old guard in Hamas’s political leadership, who are concerned with the long-running national unity talks with Mahmoud Abbas’s Fatah in the West Bank.

Since his release by Israel in 2011, Sinwar has built up his power in the secretive military wing and is believed to have ordered the execution of a top rival last year in a power struggle.

Sinwar is regarded by Israeli security officials as one of the most uncompromising of the three figures who had been leading Hamas’s military wing.

The armed wing – and Sinwar in particular – blamed the political leadership for what it saw as the failure to capitalise on the 2014 Gaza war, which ended with widespread destruction, a relative stalemate and a worsening economic and social crisis in the Gaza Strip.

Sinwar’s first significant role within Hamas was as one of the founders of the Munazzamat al Jihad w’al-Dawa [Majd] security organisation whose goal was to identify Palestinian collaborators working for Israel, some of whom were killed. He was jailed in 1989 for his part in some of those killings.

Sinwar, whose brother Mohammed is another key figure in Hamas and who helped organise the prisoner in which Yahya was released, grew up in the south of the Gaza Strip, in the refugee camp in Khan Younis.

He is regarded as the polar opposite of Meshal, both in terms of his modest lifestyle and the influence he has exercised in relative anonymity, shunning media coverage. He is described as ascetic, highly disciplined and unfazed by the prospect of violence.

Since his release – in the deal for Shalit he reportedly opposed from prison – Sinwar has apparently insisted that he would not allow any future exchanges on similar terms. It was Sinwar who reportedly torpedoed recent talks to swap more Hamas prisoners for Israeli prisoners and the remains of Israeli soldiers.

Sinwar has complained that the deal under which he was released did not go far enough, leaving other Hamas prisoners still in jail.

Yaron Blum, until recently a senior official in the Israeli domestic intelligence agency the Shin Bet, described Sinwar on Israel Radio: “He is charismatic, he is not corrupt, he is modest and he advocates action. He will do everything to maximise and gain the most from the bodies of [Israeli soldiers] Oron Shaul and Hadar Goldin and [captive Israeli] Avraham Abera Mengistu and the Bedouin that Hamas is holding. He will do all he can to carry out terror attacks.”