AMMAN(Reuters) – Jordan”s recent arrest of 12 Muslim militants has given extensive leads on how Syria is becoming a major training ground for Arab fighters heading to Iraq to join the anti-U.S. insurgency, officials said on Friday.

Security officials said interrogations of the Jordanian militants, arrested this year, have exposed how neighbouring Syria has become a haven for Sunni Muslim youths to organise clandestinely for jihad(holy war) in Iraq.

&#34We are finding that many of these people are getting help from Syrian Islamist radicals who are helping them to undergo training and financing and even equipment like explosives detonators they smuggle back to Jordan or use in Iraq,&#34 said one official involved in the case who requested anonymity.

Officials and security sources however deny there is proof the Syrian militants were operating with the consent of Damascus, an avowed enemy of radical Sunni groups it battled in the 1980s and against whom its security forces have mounted clampdowns in recent months.

But stronger bonds are developing among young militants from across the region in Iraq galvanised by fighting a common cause against U.S. troops in Iraq, officials say.

&#34They meet in Iraq and those who return home cement their ties with their associates in other Arab countries and draw others back to Iraq relying on their ability to move at greater ease in their own communities,&#34 a security official said.

A group of seven militants who are ideologically affiliated to al Qaeda were arrested last May during raids across the country, while five others from the city of Salt have been in jail since February, a security source said.

They have been indicted this week on charges that range from conspiracy to engage in terror attacks to possession of illegal arms. The conspiracy charge alone carries a death sentence.

Prosecutors say among the defendants, Khaled Sarqous, 33, who fought in Iraq, had liaised with a Syrian identified only as Abu Janah, who interrogations revealed was a mastermind behind training and financing Jordanian suicide bombers active in Iraq.

Among them was Raed Mansour al-Bannaa, whose name has been linked with carrying out post-war Iraq”s deadliest suicide bombing on February 28 that killed 125 people, mostly Shi”ites, in southern Baghdad, the state security prosecutors say.

Diplomats and political observers say Jordan”s latest arrests backs up Washington”s pressure on Damascus, which it accuses of undermining its efforts in Iraq and allowing militants to funnel fighters and cash through its territory.

Damascus says few militants cross and those who do are mostly smugglers. It says the U.S. allegations are part of pressure to extract political concessions.

But a Jordanian security official said several hundred die-hard militants with links to Syrian militants have left to Iraq through Syria since the U.S. invasion in 2003.

In a sign of Syrian ire at Jordanian accusations, Damascus announced earlier this month Jordanian &#34terrorists&#34 with ties to former Iraqi leader Saddam Hussein”s bodyguards were arrested in clashes in Damascus with security forces.

Both Washington and Amman scoffed at the Syrian allegations saying the Semadi gangsters were among the country”s most notorious thieves with a history of attacks on police but no ties to Muslim radicals.