Turkish President Recep Tayyip Erdogan speaks during a news conference to present the outcome of the G20 leaders' summit in Hamburg, Germany, July 8, 2017. REUTERS/Wolfgang Rattay

ISTANBUL: Turkish President Recep Tayyip Erdogan on Saturday said the suspects being tried on suspicion of involvement in last year's failed coup should wear uniform clothing like the notorious orange jumpsuits used at US military prison at Guantanamo Bay.

"I spoke to the prime minister and? when they appear in court, let's make them appear in uniform suits like in Guantanamo," Erdogan told a rally, after a controversy where one suspect was seen going into court with the word "hero" on a T-shirt.

Erdogan also threatened to "chop off the heads" of traitors, in the speech marking the first anniversary of a failed coup bid that aimed to oust him from power.

"First of all, we will chop off the heads of those traitors," the Turkish president told the rally in the capital city, prompting cries from the crowds that capital punishment should be restored in Turkey.

He reaffirmed that he "will sign it" if the parliament passes any bill on resuming executions.