Human Rights Watch cautioned Wednesday that over 355,000 Syrians fleeing Israel's attacks on Lebanon in the past month risk facing repression if they return home.

"Syrians escaping Lebanon, particularly men, risk arbitrary detention and abuse by Syrian authorities," the group said in a statement.

"The deaths in custody of deportees under suspicious circumstances highlight the blatant risk of arbitrary detention, abuse and persecution for those fleeing back," said HRW's deputy Middle East director, Adam Coogle.

Since Israel launched its intensive air campaign on Sept. 23, more than half a million people have fled from Lebanon to Syria, including more than 355,010 Syrians, according to Lebanese official figures.

HRW said it had documented five arrests in October.

It cited the case of a fleeing woman whose husband was "immediately" arrested by Syrian military intelligence, although they had hoped a recent amnesty, which included army deserters, would protect him.

"Syria is no safer for return than it was before, but the escalating dangers in Lebanon have left many Syrians with nowhere else to go," Coogle said.

"Their return is not a sign of improved conditions in Syria, but of the stark reality that they're being shut out of safer alternatives and forced back into a country where they still face the risks of detention, abuse and death."

Last week, Transport Minister Ali Hamieh told AFP that Israeli bombing had made a second border crossing between Lebanon and Syria inoperable – leaving only one official crossing between the neighboring countries operational.

After nearly a year of cross-border fire with Hezbollah, Israel last month ramped up strikes on the group's strongholds and then launched a ground invasion across the border.

The war has killed at least 1,754 people in Lebanon since Sept. 23, according to an AFP tally of Health Ministry figures, though the real number is likely to be higher due to gaps in the data.

The Israeli military says it has lost 37 soldiers in its Lebanon campaign since it launched ground operations on Sept. 30.