"We have arrested one Ismail Patel from Bharuch town for the November 2003 bomb blast in which many people were injured," said ATS DySP A J Chavda.
The incident happened when the bomb planted on a cycle went off.
According to Chavda, the blast was carried out to avenge the 2002 communal riots in the state.
"The accused has so far managed to remain hidden from the gaze of police and was living in Bharuch," the officer said.
Earlier, police had arrested four persons--Altaf Hussain, Mohammad Junaid Sayyad, Haaris Ansari and Javed Khan--for allegedly plotting the blast.
However, a city sessions court acquitted them due to lack of evidence in 2008 while observing that there was no evidence against them to prove their involvement in the blast or any criminal conspiracy related to the case.