Turkish authorities have arrested seven people as part of investigation into Tuesday's deadly suicide bombing that killed at least 12 people, including ten Germans, in Istanbul's main tourist area of Sultanahmet district, Prime Minister Ahmet Davutoglu said.
Turkish authorities identified Tuesday's bomber as a Saudi-born Syrian man who had recently entered the country as a migrant from Syria.
Davutoglu said the bomber was a member of ISIL, and that the government would step up its operation against the armed group until it no longer "remains a threat" to Turkey or the world.
"Turkey won't backtrack in its struggle against Daesh by even one step," Davutoglu said on Wednesday, referring to ISIL by its Arabic acronym.
"This terror organisation, the assailants and all of their connections will be found and they will receive the punishments they deserve."
ISIL has not claimed responsibility for the attack.
Germany sent a team of investigators to Istanbul on Wednesday from its Federal Criminal Police Office, to support Turkish authorities investigating the attack.
Germany's Foreign Minister Thomas de Maiziere said the number of dead Germans in Tuesday's explosion had risen to 10, but said there was no sign that Germans were specifically targeted.
"According to the investigations so far, there are no indications that the attack was directed specifically against Germans, so there can't be any connection to our contribution to the fight against international terrorism," de Maiziere said.
Germany promised Tornado reconnaissance jets to aid military effort against ISIL in Syria following the November attacks in Paris, and they started flying missions from the Incirlik air base in Turkey last week. It also sent a tanker aircraft, as well as a frigate to help protect a French aircraft carrier in the eastern Mediterranean.
Germany already was helping supply and train Kurdish forces fighting ISIL in northern Iraq but has not taken a direct combat role.
Source: Al Jazeera and agencies