Football's world governing body, Fifa, says it will open an investigation into alleged violence at the Turkey-Switzerland World Cup playoff match on Wednesday.
Fifa's Swiss president, Sepp Blatter, said sanctions against Turkey could amount to the suspension of the Turkish federation or a ban from the 2010 World Cup.
"I've never seen anything like it," Blatter said about the incidents following Turkey's 4-2 victory in Istanbul in what was the second leg of the qualifying round.
"That makes me angry. Something is wrong in football if that can happen," Blatter told Swiss radio.
He told a news conference later on Thursday that he was speaking as Fifa president, and not as a Swiss.
"We will act fast and harshly," added Blatter. "It was not fair play. The Turks had an opportunity to show they were welcoming hosts and that revenge was not an option in football."
Turkey criticised Blatter for his comments on the violent scenes that followed Wednesday's match.
"I am disappointed to hear the statements of the Fifa president before the reports of the match are unveiled," Mehmet Ali Sahin, state minister responsible for sports told journalists.
"He spoke as a Swiss fan instead of as a president ... These kinds of statements are misleading to decision-makers," he continued.
Turkish players and coaches complained of ill treatment after the first leg of the playoffs in Bern. The Turks say they were insulted by the Swiss press, players and coach and that Swiss fans blew whistles throughout the playing of the Turkish national anthem.
The two teams tied 4-4 on aggregate, but the Swiss advanced to next year's World Cup in Germany on away goals.
After the final whistle in Istanbul, both teams raced from the field to escape angry fans. Swiss midfielder Benjamin Huggel was seen to kick a member of the Turkish coaching staff as he ran off the pitch before Turkish defender Alpay aimed a kick at Marco Streller.
Television footage then showed a melee breaking out in the tunnel on the way to the locker room involving several players.
Swiss defender Stephane Grichting was injured and hospitalised with a groin injury, according to the Swiss Football Association. The team doctor said that he is not expected to be able to play for a week at least.
Blatter said Fifa would consider a range of severe sanctions against Turkey.
"Anything can happen - from nothing at all to the suspension of the Turkish federation or even a ban on participation in the next World Cup," he said.
Fifa's president said the investigation would also show if the Swiss themselves were out of line. "We will question both teams, because the Swiss want to give their version about what happened," he added.
But Turkish Football Federation chairman Levent Bicakci rejected Blatter's analysis.
"Our Federation finds the Fifa president's statement really odd and we will do whatever we can to clarify this event and to make sure that Switzerland gets the same penalty as Turkey," he told a news conference.
Turkey has already been warned and fined twice by Fifa because of its supporters' behaviour during earlier qualification matches for next year's World Cup.
Blatter did not go into detail about Wednesday's violence and said Fifa would await the report from the match officials in Istanbul. Anyone accused will be able to defend himself, he said.
Tensions had been mounting since the first match on Saturday in the Swiss capital, Bern, which Switzerland won 2-0. The Turkish team complained of poor treatment.
Turkey's coach Fatih Terim said Swiss striker Alex Frei cursed at him and made an obscene hand gesture after the first match, a claim the player denied.
The Swiss said they were subjected to hostile treatment when they arrived in Istanbul on Monday, including being held up for several hours in passport control. Fans taunted the players and reportedly threw eggs and rocks at the team bus as it left the airport.
No diplomatic reaction
The Swiss foreign ministry has so far not reacted to the alleged incidents. Ministry spokesman Jean-Philippe Jeannerat told swissinfo that diplomats were focusing on helping Swiss supporters return home for the time being.
"We are still considering whether we should initiate some kind of diplomatic response," he added.
The Swiss foreign minister, Micheline Calmy-Rey, has already sent a letter to her Turkish counterpart to complain about the reception given to the national squad upon their arrival in Turkey.
swissinfo with agencies
Turkey won 4-2 against Switzerland in the second leg match in Istanbul.
Goals: Frei 1; Sanli 24, 38; Ates 52; Streller 84; Sanli 89.
It followed Switzerland's 2-0 victory on Saturday in Bern.
The aggregate score was 4-4, but the two away goals were enough to ensure that Switzerland went through.