Hamas security forces in Gaza have detained members of the Palestinian militant group which claims to have abducted BBC reporter Alan Johnston.
Alan Johnston has been held since 12 March
Among the arrested was Khattab al-Maqdisi, a spokesman of the Army of Islam group, Hamas said.
"The arrests were carried out after all negotiation attempts... failed to free the abducted journalist," the Hamas-run interior ministry said in a statement.
Alan Johnston was kidnapped in Gaza on 12 March.
The BBC is holding a rally for Mr Johnston on Monday to mark the 16th week since his disappearance.
"The arrests are targeting figures who were involved in the abduction of the journalist," the interior ministry statement said.
The Army of Islam is influenced by al-Qaeda
It said Hamas acted after "the use of peaceful means failed to free" the British reporter.
Earlier, Hamas spokesman Sami Abu Zuhri said Mr Maqdisi was detained after he opened fire on members of Hamas's security forces in Gaza City.
He said Hamas would investigate claims by the Army of Islam - a small armed group - that Mr Maqdisi was injured during the arrest.
Mr Abu Zuhri also accused the clan which allegedly controls the Army of Islam of abducting 10 Hamas students.
Tensions between Hamas and the Army of Islam have been growing since Hamas seized control of the Gaza Strip last month by force.
Hamas has demanded that the Army of Islam release Mr Johnston, threatening to "use all means to secure his life and to free him".