The Federal Reserve's $600 billion bond purchase program will be completed as planned, top Fed officials signaled on Monday, though they saw heightened economic uncertainty from unrest in the Middle East.

U.S. central bank officials from Atlanta, Chicago and Dallas said they were keeping an eye on the risk higher oil prices could feed through into broader inflation, as well as their potential to hurt growth.

Atlanta Fed President Dennis Lockhart said he would not rule out more bond buys if the recovery dwindles. Dallas Fed President Richard Fisher said he would vote to end the program

early if higher oil prices fed into broader inflation.

The program, announced in November to bolster a fragile economic recovery, is due to end in June. Since it began there have been signs the recovery is picking up steam.

Lockhart, a policy centrist, said he was more concerned about the risk to growth from the oil price rise. He said he would be very cautious about increasing the size of the purchase program.

Given the emergence of new risks, however, I prefer a posture of flexibility, Lockhart said.

He expected overall price pressures to remain subdued and warned it is too early to declare a jobs recovery as firmly established.

Fisher, an inflation hawk, said he fully expected the $600 billion program to run its course.

Fisher told an international bankers' conference he would vote to curtail or stop the program, however, if it proves to be demonstrably counterproductive.

The Fed meets on March 15 for its policy-setting meeting, at which it is expected to reaffirm its purchase plan. Fisher is a voter on monetary policy this year, Lockhart is not.

In a CNBC interview, Chicago Fed Bank President Charles Evans said the Fed was closely watching rising oil prices, adding that they were obviously a headwind for growth.

Revolutions beginning in Tunisia and Egypt have spread to other countries in the region, including Libya and Bahrain. This has pushed the price of oil above $100 a barrel, complicating the Fed's objective of stimulating economic growth while keeping prices under control.

That said, Evans pointed to the improving job market and said he expected economic growth of 4 percent this year and next. He called the size of the purchase program good.

I continue to think the hurdle is pretty high for altering our currently announced program, Evans, seen as a monetary policy dove and one of the most outspoken proponents for quantitative easing, said. Evans does not have a vote on monetary policy this year.

Fisher said the question will be whether the oil price rise is sustained.

It is really a question of how that works its way through, he said. We have already seen very high gasoline prices. That's one of the ways that it most affects the consumer.

(additional reporting by Pedro Nicolaci da Costa and Rachelle Younglai; Editing by Andrew Hay)