BAGHDAD — Iraq is paying for more of its own reconstruction but is still struggling to spend its multibillion dollar surplus as it copes with a flood of oil revenue and a cumbersome approval process meant to curb corruption, U.S. officials said today.

Iraq could finish the year with as much as a $79 billion budget surplus as oil revenues add to leftover income the Iraqis still haven’t spent on national rebuilding, according to a report by the Government Accountability Office made public Tuesday.

In Washington, senators renewed calls for Baghdad pay more for its own reconstruction, which has been heavily supported by hard-pressed American taxpayers.

“The Iraqi government now has tens of billions of dollars at its disposal to fund large-scale reconstruction projects,” Sen. Carl Levin, D-Mich., said in a statement.

“It is inexcusable for U.S. taxpayers to continue to foot the bill for projects the Iraqis are fully capable of funding themselves,” Levin said.

But U.S. officials who work with the Iraqis on reconstruction said the Baghdad government has been increasing its capital spending by 30 to 35 percent each year since 2006 — although they added that both governments want to see the pace increased.

The Iraqi government is drafting plans for Iraqi-funded projects to include 1,000 new primary health care centers over the next 10 years, new airports and a major renovation project for downtown Baghdad, the American officials said.

They spoke on condition of anonymity because they did not want to comment on Iraqi government performance.

The officials said the United States has not begun any new reconstruction projects in Iraq since 2004 and that ongoing work is funded by money approved by Congress four years ago.

In the report, the GAO said Iraq had an estimated cumulative budget surplus of about $29 billion from 2005 to 2007 and could have another surplus of up to $50 billion this year.

The expected surplus is likely to be lower because parliament today approved legislation for a $22 billion supplemental budget for 2008.

Nevertheless, the GAO report faulted the government for holding back on spending plans.

“First ... (the) relative shortage of trained budgetary, procurement and other staff with the necessary technical skills as a factor limiting the Iraqi government’s ability to plan and execute its capital spending,” the GAO said.

A second problem is the government’s weak accounting systems, according to the report.

“Third ... violence and sectarian strife remain major obstacles to developing Iraqi government capacity,” it said.

The report also estimated that this year Iraq could generate $67 billion to $79 billion in oil sales. Other U.S. officials previously had said they expected the oil windfall to be about $70 billion.

“This substantial increase in revenues offers the Iraqi government the potential to better finance its own security and economic needs,” the GAO said.

But the U.S. officials said the influx of oil money had been difficult to manage, not only for Iraq but for other oil-producing countries.

Other problems cited by the officials included a cumbersome approval process — put in place to curb corruption — lack of expertise in the ministries and a shortage of Iraqi contractors capable of taking on major development projects.

Since 2005, the United States has funded a number of efforts to teach civilian and security ministries how to effectively execute their budgets.

The efforts included programs to advise and help Iraqi government employees develop the skills to plan programs and to effectively deliver government services such as electricity, water and security.