Among the convicts, eight were sentenced to 13 years imprisonment while nine others to nine years.
Also read: Series bomb blasts: Sylhet JMB leader gets life term
Satkhira Additional District and Sessions Judge Mohammad Shariful Islam handed down the verdict.
The court also acquitted one accused Abul Khayer as allegation brought against him could not be proved.
The convicts are Maniruzzaman, Nur Ali, Gias Uddin, Ismail Habibur, Bilal Hossain, Mamtaz Uddin, Mahbubur Rahman Liton, Rakib Hossain, Monwar Hossain Ujjal, Asadur Rahman, Anisur Rahman, Alamgir Hossain, Nasir Uddin, Fakhruddin Raji, Asaduzzaman and Naimuddin.
Of them, Fakhruddin, Asaduzzaman, Naimuddin were tried in absentia.
Besides, another accused, Nasiruddin Dafadar ,died on December 26, 2018 at Satkhira jail.
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According to the prosecution, five bombs went off in different parts of Satkhira district including Shaheed Razzak Park, District Court premises, Women and Children Repression Tribunal premises and bus terminal on August 17, 2005 during the nationwide series bomb blast.
Five cases were filed in this connection and police submitted chargesheet against 19 people in the case on March 13, 2006.
On Tuesday, police produced the accused in the cases before the court which granted bail to two accused--Mamtazuddin and Nur Ali—considering their old age.
Abdus Samad, additional public prosecutor, said a number of bombs went off simultaneously in different parts of the district on August 17, 2005.
Also read: Series bomb blast: Two JMB men get life imprisonment
The trial in the case started on February 14, 2008.