Attacking targets in Syria in retaliation for Assad regime mortar shells landing in the Golan Heights may be an attempt by the Israeli prime minister to gain popularity on the security front three months before elections.

Analysts say Benjamin Netanyahu, who is seeking a third premiership in the January poll, could be trying to shift public attention to the country's northern border with Syria and away from its southern border, where Israel has been unable to stop rocket attacks on its communities from Hamas-ruled Gaza.

"There is public criticism that the government is doing very little to defend the people in the south from rocket attacks. So instead of going on an all-out operation in Gaza that nobody wants, the government is showing toughness in the north," said Meir Zamir, a professor in the Middle East studies department at Ben-Gurion University.

Tension began rising on Sunday when the Israeli army launched an anti-tank missile into Syria as a warning after an errant shell fired in hostilities between Syrian soldiers and insurgents landed in the Israeli-occupied Golan Heights.

On Monday, after another stray shell fell on one of Israel's posts in the Golan, Israel shelled a Syrian artillery battery. It was the first confrontation between the Israeli army and Syria on the typically quiet ceasefire line in the Golan since the 1973 Arab-Israeli war.

The exchanges have raised fears that, for the first time since the Syrian conflict began last year, Israel could be dragged in.

However, despite charges that Israel's reaction was politically motivated, Israeli experts appear mixed on a possible escalation between Tel Aviv and Damascus.

"This could develop into a more serious escalation. That's because anarchy is now reigning in Syria, the regime is not in control over a large part of the country, and there is fighting between the army and insurgents close to the armistice line," said Itamar Rabinovich, a former Israeli ambassador to the US and the country's chief negotiator with Syria in the early 1990s.

Mr Rabinovich said Israel was not interested in an escalation but was monitoring the fighting in Syria close to its border, and the firing of shells was "a signal that it will not tolerate the war" spilling over into the Golan Heights.

Mr Zamir, the professor from Ben-Gurion, however, claimed such an event was unlikely. "Israel's reaction seems a bit out of proportion. There was no serious damage done and everybody's reading it as unintentional. It's very difficult to pinpoint mortar shells and it's clear nobody was intending to fire them on Israel."

Some Israeli analysts warned that the country's leaders were growing concerned about Islamist groups becoming more active in Syria as part of Damascus's power struggle and initiating cross-border attacks on Israel.

Amir Rapaport, an Israeli commentator on security matters, wrote yesterday on the news website NRG that Israel fears facing clashes with Islamists in the north similar to the hostilities on its southern frontier with Islamist groups in Gaza.

He wrote: "Scenarios that no longer seem unrealistic show the Israel-Syria border … will turn into territory in which global jihad fighters who've been gaining strength in Syria will act without intervention, just like they have succeeded in setting the rules of the game in Gaza."

Israeli officials have said this week's mortar fire came from Syrian army tanks. The Syrian Observatory for Human Rights, a Britain-based opposition group, said Syrian soldiers and rebels have been exchanging fire in the village of Bir Ajam, less than a kilometre from the Israeli border. However, it did not say whether the stray shell came from government forces.

Israeli leaders have played down the possibilities of an escalation of violence between Israel and Syria and have even suggested that Israel would be willing to grant asylum to Syrians escaping the fighting in their home country.

Shimon Peres, the Israeli president, told CNN on Monday: "We never took the initiative to fire … we don't consider that we should or can intervene."

And Michael Oren, Israel's ambassador to Washington, told CNN that a flood of refugees heading from Syria into Israel was more probable than a breakout of fighting between the hostile neighbours.

"We'd give them refuge. These are populations with which we have good relations. It's not unprecedented. We have been prepared for it for a long time but it hasn't happened," he said.