Lebanon's Hezbollah chief Hassan Nasrallah, in his first public appearance in more than three years, warned those banking on change in the Arab world that he would arm his fighters more heavily than ever.

Marking the Shiite commemoration of Ashura, Nasrallah spoke in person to a frenzied crowd of tens of thousands in his stronghold in Beirut's southern suburbs for only a few minutes, joking: "Don't go away, I'll be right back on that screen" before being whisked away by nervous-looking bodyguards.

In a speech broadcast on large screens shortly after his departure, Nasrallah vowed his Iranian-backed group would continue to arm in the face of possible "regional change," hinting at neighbouring Syria.

"A message to all those who are conspiring against the resistance and banking on change (in the Arab world)... We will never let go of our arms," said the black-clad Shiite leader.

"We are tens of thousands of trained fighters, who are all ready to die," he said.

"Day after day, the resistance gains more fighters, trains better fighters and arms even more heavily.

"Every weapon that rusts is replaced."

Many observers say the Syria crisis, which is threatening to topple the regime of Hezbollah's ally President Bashar al-Assad, has dealt a severe blow to the Lebanese group.

Considered a prime target for his arch-enemy Israel, Nasrallah last appeared in public in July 2008, when five Lebanese prisoners were released by the Jewish state.

On Tuesday, he was captured on camera making his way toward a stage as his ecstatic supporters pushed and shoved to get close to the leader, who was heavily guarded by a swarm of men dressed in black.

Nasrallah appeared relaxed as he strode to the stage, where he spoke for a few minutes before being ushered away.

He also lashed out at the United States for seeking to destroy Syria in order to "make up for its defeat in Iraq."

"The United States has tried to portray itself as the defender of human rights and democracy in the Arab world.

"These charlatans and hypocrites are known for their support of all dictatorships that collapse and for disowning these dictatorships immediately after they collapse.

"This is the character of Satan."

Nasrallah renewed his vow to stand by Assad and lashed out at the Syrian National Council, the main anti-Assad opposition group, for aiming to "destroy Syria" while moving closer to Washington and Israel.

"The so-called Syrian National Council, formed in Istanbul, and its leader Burhan Ghalioun... are trying to present their credentials to the United States and Israel," Nasrallah said.

His comments came after Ghalioun was quoted as saying a Syria run by the country's main opposition group would cut military ties to Iran, Hezbollah and the Palestinian Islamist movement Hamas.

"There will be no special relationship with Iran," Ghalioun, a 66-year-old university professor, told the Wall Street Journal in an interview published on Friday.

"Breaking the exceptional relationship means breaking the strategic, military alliance," he was quoted as saying. "After the fall of the Syrian regime, (Hezbollah) won't be the same."

Iranian- and Syrian-backed Hezbollah, blacklisted as a terrorist organisation by Washington, last fought a devastating war with Israel in 2006 that left much of Lebanon in ruins.