Turkish police have made 20 arrests and are looking for another 20 people following the pitch invasion that caused the abandonment of Sunday's Istanbul football derby between bitter rivals Galatasaray and Besiktas.
The invasion could be linked to recent riots in Turkey which were led by the Besiktas fan club the Carsi Group.
The Turkish Minister of the Interior refused to say which club the fans supported, although it is believed to be two sets of rival Besiktas fans.
The fans invaded the pitch, throwing seats at tear gas-firing police after Galatasaray midfielder Felipe Melo had been red-carded in the second minute of injury time.
Besiktas lost the match 2-1.
The Carsi Group led the anti-government protests sparked by a local campaign to save Istanbul's central Gezi Park from demolition.
The action broadened into nationwide demonstrations against the ruling party, seen as increasingly authoritarian.
Another group of Besiktas fans, the 1453 Group, which is the date when the Ottomans seized the capital of the Eastern Roman Empire Constantinople (what is now Istanbul), support the Government led by Prime Minister Recep Tayip Erdogan.
