Iraqi cleric Moqtada al-Sadr on Friday insisted that claims his supporters were involved in fighting in Syria were false, but said members of "splinter" groups could be involved in the violence.
"All these claims are lies," Sadr, a powerful Shiite cleric, said in a written response to a question from one of his followers over allegations that Sadrists are taking part in the violent suppression of the ongoing uprising against the Syrian regime.
He added that any purported video evidence of involvement of one of his loyalists are "fabricated and not real".
"They do not belong to me," Sadr said of fighters in Syria, adding that it was possible that members of "splinter" groups supported by external parties were involved the violence.
Sadr did not specify which splinter groups he was referring to, or give details on which external parties may be supporting them.
The cleric promised to punish any of his supporters who were proved to be involved in the Syrian unrest.
Syria, which has witnessed an uprising for more than a year, shares a 600-kilometre (370-mile) border with Iraq.
In recent months, Iraqi officials have warned of weapons being smuggled to anti-government fighters and the movement of Sunni militiamen to Syria from Iraq.
More than 13,500 people have been killed in the crackdown on dissent that followed the eruption in mid-March 2011 of anti-government protests and the increasingly violent insurgency against Assad's regime, according to the Syrian Observatory for Human Rights.