JERUSALEM — Israel's military launched a surprise large-scale exercise on Wednesday on the occupied Golan Heights, testing its battle readiness amid tensions over Iran's nuclear drive and civil war in Syria.

A military spokeswoman, appearing to play down any speculation the drill heralded imminent hostilities with Iran or Syria, said it was part of a routine training schedule. A similar snap exercise was held around this time a year ago.

Israel has urged world powers to set a red line for Tehran's nuclear program, saying time was running out to stop what it sees as its quest for atomic arms and raising international concern it could launch a go-it-alone strike against Iran.

In the early hours of the morning, reservists were summoned from their homes by telephone after the end of the two-day Jewish New Year's holiday and told to report for duty.

Along with units of conscript soldiers, the troops were to be flown by helicopter from central Israel to the Golan Heights bordering Syria for a live-fire exercise, due to end later in the day and overseen by the chief artillery officer.

Israel Radio said the drill simulated a sudden outbreak of hostilities on Golan Heights that would require swift troop deployment. The radio's military affairs correspondent, who is briefed regularly by senior officers, said the timing of the exercise was "not mere coincidence."

In a brief statement, the military said the exercise had been ordered by its chief of staff, Lieutenant-General Benny Gantz, "to examine the competence and preparedness of several units in the Israel Defense Forces."

The statement gave no troop figures, but Israel Radio said large contingents were involved. Military sources said an even bigger exercise, which was announced in advance, was held for several days along the border with Lebanon two weeks ago.

Iran denies it is seeking nuclear weapons. It has vowed to strike back against Israel, widely believed to be the only country in the Middle East with atomic arms, if it is attacked.

Israel fears such retaliation could include rocket salvoes from Iran's guerrilla allies in Lebanon and Gaza. It is also concerned rogue elements in Syria could seize chemical weapons and launch attacks on the Golan.

Israel captured the Golan Heights in a 1967 Middle East war and annexed the area, in a move that was not recognised internationally, in 1981.