Beirut -- A German judicial delegation is expected to arrive in Beirut in July to question one of the would-be bombers of a German train who was tried and sentenced in Lebanon, Lebanese judicial sources said on Tuesday.

"A German judicial delegation was given permission by the general prosecutor Saaed Mirza to come to Beirut to question Jihad Hamad as a witness on July 3rd," the sources told DPA.

Hamad's lawyer, Fawaz Zakariyeh, said that he will also be present at the questioning.

A Lebanese court in December 2007 sentenced Hamad to 12 years of hard labour for the failed 2006 attempt to bomb two trains in Germany and acquitted three other defendants who were held with him in Lebanon.

The four were charged with planting crude bombs on two trains at a station in the western German city of Cologne on July 31st, 2006. Due to faulty detonators the bombs failed to explode.

Three of the accused -- Khaled Khair-Eddin el-Hajdib, Ayman Hawa and Khalil al-Boubou -- were acquitted by the Beirut Criminal Court.

The main suspect in the operation, Lebanese citizen Youssef el- Hajdib, is currently being held in Germany.

Both of the men convicted are accused of trying to blow up two trains in Dortmund and Koblenz, the two towns near which the separate trains were located when the bombs were discovered.

Fingerprints and DNA evidence led to the arrest of el-Hajdib after information was supplied by Lebanon's secret service.

Police said the bombs -- which were supposed to explode simultaneously -- failed to detonate because of a construction error.