WASHINGTON, United States (AFP) — President Barack Obama called on Turkey to respect the rule of law Saturday, a warning to the country’s government as it rounded up alleged coup plotters.

He stressed the “vital need” for all parties to “act within the rule of law,” after consulting key national security aides about the fallout from a botched coup.

Obama also urged Turkish leaders to “avoid actions that would lead to further violence or instability,” the White House said.

Although the government of Recep Tayyip Erdogan has repelled the coup, the situation remains fraught and tensions between Washington and Ankara are growing.

Several army commanders, a top judge and more than a thousand military personnel have swiftly been detained after the failed power grab that killed more than 200.

There was no indication that Americans have been killed, Obama said. But a new crisis appears to be taking hold.

The Turkish authorities have imposed a security lockdown and cut power to the Incirlik air base in the south of the country.

The facility, 68 miles (110 kilometres) from the Syrian border, is home to a stash of nuclear weapons and 1,500 US troops.

The US military command in Europe ordered American forces across Turkey to take maximum protective measures.

During the coup attempt, Obama threw his support behind Turkey’s “democratically elected government” and urged all parties to “avoid any violence or bloodshed.”

But there are growing concerns about a government crackdown on Erdogan’s opponents and what that may mean for a key ally in NATO.

Almost 24 hours after the coup, there was still no word from the White House on whether Obama had spoken to Erdogan.

In public appearances since returning to Istanbul, Erdogan has blamed the attempted coup on followers of Pennsylvania-based opposition figure Fethullah Gulen, a Turkish preacher with a large following.

US Secretary of State John Kerry said the United States will help Turkey investigate the failed coup and invited Ankara to share any evidence it has against Gulen.

Turkey had not yet issued a formal extradition request, he added.

Even before Friday’s bloody drama, Obama had voiced concern about Erdogan’s respect for the rule of law.

“He came into office with a promise of democracy,” Obama said in April. “That’s the legacy he should pursue,” he added, warning against the “repression of information and shutting down democratic debate.”