The small blast occurred on a plane that had come from the Aegean port city of Izmir, Turkish Airlines said in a statement.
A worker, who had been cleaning the plane, lost fingers after picking up a package that appeared to be a wallet that had been left on the aircraft, the airline said.
Two others also sustained minor injuries.
The Anatolia news agency said authorities believed two grammes of C-4 plastic explosives were inside the package.
Television showed what appeared to be a Boeing 737 at the airport. No damage could be seen on the outside of the plane. An ambulance was seen driving away from the plane. A fire truck could be seen nearby.
Private CNN-Turk television said the explosion occurred around the time US Secretary of Defence Donald Rumsfeld was set to leave Istanbul, although a US official could not confirm that report.
Security is extremely tight in Turkey, which is hosting a summit of NATO leaders in Istanbul.
Guests include US President George Bush, French President Jacques Chirac and British Prime Minister Tony Blair.
Middle East reform
Earlier, using Turkey and the day-old sovereign government in Iraq as models, Bush urged people in the Middle East to embrace democracy fashioned in their own image.
"I believe that freedom is the future of the Middle East, because I believe that freedom is the future of all humanity," Bush said in a speech to students at Galatasaray University on the banks of the Bosphorus.
Bush used Turkey as a model for
democracy in the Middle East
The US leader, wrapping up his maiden visit to Turkey, worked to soothe worries in the Muslim and Arab worlds that his frequent calls for political reforms in the Middle East mask an effort to impose US values.
Citing Islam's stated commitment to justice, Bush said "Turkey
has found what nations of every culture and every region have found: If justice is the goal, then democracy is the answer."
A day after Iraq's interim government took power, Bush said that country was now a battleground pitting "political extremism and civilized values" against each other and that democracy would triumph despite deadly unrest there.
He thanked NATO leaders meeting in Istanbul for agreeing to help train Iraq's nascent security forces, calling that decision "a great advantage and crucial success for the Iraqi people."
Bush said that Western nations, including the United States, had propped up or tolerated repressive regimes in the past in a vain attempt to "purchase stability at the price of liberty" that yielded neither.
"It has not made Western nations more secure to ignore the cycle of dictatorship and extremism. Instead we have seen the malice grow deeper, and the violence spread, until both have appeared on the streets of our own cities," he said.
"A free and sovereign Iraq is also a decisive defeat for extremists and terrorists, because their hateful ideology will lose its appeal in a free, tolerant, successful country"
Bush spoke after winning support for a watered-down version of his Broader Middle East Initiative, which aims to promote democratic and free-market reforms throughout the volatile region.
The president said democracies "reflect their people, every
democracy has its own structure, traditions, and opinions" but also adhere to bedrock principles that must not be compromised.
"The promise of democracy is fulfilled in freedom of speech, the rule of law, limits on the power of the state, economic freedom, respect for women, and religious tolerance," he said.
No overstaying welcome
British Prime Minister Tony Blair said the US-led occupation forces could only stay in Iraq as long as they were wanted and urged the Iraqi people to have faith in their future.
"We can only stay in Iraq insofar as you wish us to stay," Blair said in an interview with an Iraqi television station.
Blair: 'We can only stay in Iraq as
long as you want us'
"If you don't wish us to stay, we have no right to be there," he told Pentagon-funded Iraqiya TV in Istanbul, where he was attending a NATO summit. Told by the Iraqi interviewer that Iraqi people were living in hell, Blair said: "The enemy is not the people trying to help make the country better, the enemy are the terrorists."
Asked what his message was to the people of Iraq, Blair replied: "I would say: have confidence and faith because you will succeed."
"You needn't fear for the future. You will make it because we will help you make it," he said. "I would say have confidence, have faith and we will be there as a friend."