U.S. President Barack Obama has offered aid to Turkey's President Recep Tayyip Erdogan in the investigation of last week's attempted coup.
The White House said Obama and Erdogan spoke by telephone Tuesday, four days after the coup attempt in Ankara. Obama made clear that the United States will "provide appropriate assistance" to the investigation.
The two men also discussed Turkey's request that Muslim cleric Fethullah Gulen be extradited from the U.S. to face charges that he was linked to the coup attempt. A White House spokesman did not give details about the U.S. position on Gulen's possible extradition, except to say the decision will be made according to a longstanding treaty between Ankara and Washington.
In his phone call with Erdogan, Obama strongly condemned the coup attempt and urged that investigations and prosecutions related to the uprising be conducted in ways that reinforce public confidence in democratic institutions and the rule of law, according to the White House.
WATCH: Gulen denies Erdogan claims of coup involvement
Earlier Tuesday, Turkey escalated its purge of teachers and civil servants suspected of involvement in the failed coup. The government fired more than 26,000 people, while sending dossiers to Washington alleging that Gulen, an ex-ally of Erdogan who now lives in the eastern U.S. state of Pennsylvania, was behind the putsch.
Turkish media reported that the education ministry fired 15,200 teachers across the country, while the interior ministry dismissed nearly 9,000 workers. Another 1,500 in the finance ministry were fired, as were hundreds more in the religious affairs directorate, the family and social policy ministry and prime minister's office. The country's higher education board demanded the resignations of 1,577 university deans.
The firings came on top of about 9,000 people Ankara has detained for suspected involvement in the attempted overthrow of President Recep Tayyip Erdogan's government.
In another telephone call Tuesday , U.S. Secretary of Defense Ash Carter spoke with Turkish Minister of Defense Fikri Işik. The Turkish official assured Carter that Turkey remains a determined and committed partner and ally in the fight against terrorism.
WATCH: White House spokesman condemns Turkey coup
Işik had planned to attend a ministerial meeting that Carter is hosting Wednesday in Washington on countering Islamic State, but now says he must remain in Turkey.
Turkey has sent files to the U.S. on Gulen, who has lived in the United States since 1999. In Washington, the State Department confirmed that Washington did receive some "materials" from Ankara, but that it is working with the Justice Department to review and analyze "whether they constitute a formal extradition request."
Gulen lives in Pennsylvania on the grounds of the Golden Generation Worship & Retreat Center, an Islamic facility founded by Turkish Americans. His philosophy mixes a mystical form of Islam with staunch advocacy of democracy, education, science and interfaith dialogue. His movement operates dozens of charter schools in the U.S.
Gulen continues to exert considerable influence in Turkey, with supporters in the media, police and judiciary.
Erdogan and Gulen were once allies, but had a falling out over 2013 corruption investigations in Turkey, which the Turkish leader blamed on Gulen.
The exiled Gulen has also criticized Erdogan's increasingly authoritarian rule, while the Turkish leader has carried out a broad campaign against Gulen's movement.
Erdogan said Sunday he is receptive to reinstating the country's death penalty in the aftermath of the coup attempt. But EU foreign policy chief Federica Mogherini warned that such a step may end Turkey's EU membership hopes.
"Let me be very clear," she said. "No country can become an EU state if it introduces the death penalty."
Turkey hasn't executed anyone since 1984, and capital punishment was legally abolished in 2004 as part of Turkey's bid to join the European Union.
VOA's Nike Ching contributed to this report.