The report by the special inspector general for Afghanistan, John Sopko, warned that handing over security to Afghan forces as the US withdraws its troops would also likely balloon the costs of US-funded aid schemes.

"The United States risks wasting billions of dollars if US-funded development programs cannot be sustained, either by the Afghan government or by continued donor support," said the report to Congress released on Monday.

"As this report to Congress illustrates, a decade of struggle and bloodshed - and more than $89 billion of US appropriations for Afghan reconstruction - has not cleared the landscape of serious problems," Sopko writes.

He adds that a "significant portion of the US government's $400 million investment in large-scale infrastructure projects in fiscal year 2011 may be wasted, due to weaknesses in planning, co-ordination and execution".

Audits of various projects taking place across the country found significant construction problems and flaws.

Three police border posts in eastern Nangarhar province were found to have major construction faults, including poorly built guard towers, unconnected drains and badly installed heating and ventilation systems.

"These problems included the lack of a viable water supply, a poorly constructed septic system, and inadequate sewage," the report notes, adding nothing has been repaired as there is no effective quality assurance in place.

The basement of one of the buildings was now being used as a chicken coop, it added.

Following complaints about shoddy workmanship, there had been arrests and charges brought in both the United States and Afghanistan and more than $900,000 had been recovered.

Several contracts were also withdrawn when poor contractors were uncovered, leading to the protection of some $50 million in contract funds. Two people had been convicted, one of theft and conspiracy.

"Implementing projects that the Afghan government is unable to sustain may be counteroductive" to the US counterinsurgency mission, Sopko said in the report.

"If goals are set and not achieved, both the US and Afghan governments can lose the populace's support."

The analysis examines the Afghan Infrastructure Fund, which was authorised by Congress in 2010. Over the past two years, Congress has invested $800 million into the fund, and the State Department has committed about $1 billion of its funds to related infrastructure programs.

The report comes as NATO countries have already started to withdraw their 130,000 troops after more than 10 years of war, with all combat forces due to leave by the end of 2014.