Lebanon's Hezbollah has declared itself more than a guerilla movement after images emerged showing it staging a military parade in Syria, where it is fighting to bolster the regime.

The images shared widely on social media provoked controversy in Lebanon, where the Shia movement is a divisive force, as well as concern from Washington, which deems Hezbollah a "terrorist" group.

"We now have a trained army and the Resistance (Hezbollah) does not need to rely on guerilla tactics," the daily Al-Safir on Wednesday quoted Hezbollah's second-in-command Sheikh Naim Qassem as saying.

Hezbollah's media department disputed that quote, insisting Qassem had actually said: "We have become more than a guerilla movement but less than an army."

"We are better equipped, better trained and we have sophisticated capacities," the second-in-command was quoted as saying by Al-Safir.

Qassem confirmed that Hezbollah had recently held a military parade in the Syrian town of Qusayr near the Lebanese border.

Hezbollah retook the town from Syrian rebels in 2013 in its first major victory after it intervened in the Syrian conflict in support of President Bashar al-Assad's regime earlier that year.

Photos of tanks, armoured vehicles and anti-aircraft batteries displaying the Shia movement's yellow flag have appeared on social media in recent days.

Hezbollah's militia never disarmed after Lebanon's devastating 1975-90 civil war and is the country's most powerful armed force.

Detractors accuse it of being a "state within a state" and Washington has designated it a "terrorist" group since 1995, accusing it of a long list of attacks including the bombing of the US Embassy and Marine barracks in Lebanon in 1983.

Washington supplies equipment to Lebanon's army and a State Department spokeswoman said this week that the US would be "gravely concerned" if it ended up in Hezbollah's hands.