Turkey's leaders promised a tough fight against Kurdish militants but said Thursday that would not mean backtracking on reforms critical to their bid to join the European Union.

Hours later the European Commission demanded an investigation into ongoing violence that has left 16 dead after a week of the worst street clashes in decades. Two EU legislators accused Turkey of breaking international law by using pistol fire to disperse pro-Kurdish demonstrators.

Foreign Minister Abdullah Gul vowed Thursday that Turkey was determined to fight rebels without sacrificing democratic reforms.

He promised a "sharper struggle against terrorism" but said: "Turkey's democratic standards will increase and strengthen; there will be no question of going back from democratic steps taken."

Kurds have said the government response to the demonstrations has been excessive and failed to deal with the roots of the problem.

Prime Minister Recep Tayyip Erdogan has said the problems in Turkey's overwhelmingly Kurdish southeast would be solved through democracy, but he has refused to meet with the leading pro-Kurdish party, the Democratic Society Party.

Kurdish politicians say that Erdogan's government met with leaders of Hamas, the Palestinian group that is on many countries' lists of terrorist organizations, and should be willing to meet with the pro-Kurdish party, which swept local elections in much of the southeast.

A court in southeast Turkey on Thursday ordered the arrests of four Kurdish politicians from the Democratic Society Party suspected of taking part in the funerals of 14 Kurdish rebels last week. The funerals were the spark for the riots.

The arrests came amid continued violence across the country. A Kurdish militant group on Wednesday claimed responsibility for the bombing of an Istanbul office of Erdogan's party that wounded two party workers. Separately, officials in the southeast on Wednesday reported the deaths of six more security officers.

The Democratic Society Party called in a statement for greater cultural and linguistic rights for Kurds, as well as a general amnesty for the rebels.

The government often accuses the Democratic Society Party of links to the Kurdistan Workers' Party, or PKK, the banned rebel group considered a terrorist organization by Turkey, the United States and the European Union. The fight with the autonomy-seeking PKK has left some 37,000 dead in Turkey since the group took up arms in 1984.

A violent offshoot of the PKK, the Kurdistan Freedom Falcons, has promised more bombings in response to the unrest and has claimed responsibility for two bombings since Friday.
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Associated Press writers Benjamin Harvey in Istanbul and Suzan Fraser in Ankara contributed to this report.