Parliament speaker Volodymyr Litvin said after a meeting with British ambassador Robert Brinkley that "reservations" had been expressed about Ukraine's export control system.
Earlier on Tuesday, US and British officials submitted a report by the experts to the Ukrainian Government, but its findings have not yet been made public.
The experts spent a week in Ukraine in October investigating claims that Kiev had sold Kolchuga early-warning radar systems to Iraq in breach of United Nations sanctions.
The US also alleges that Ukrainian President Leonid Kuchma personally approved the sale.
The government has so far refused to comment on the report, but has strongly denied the allegations.
Olena Hromnytska, a spokeswoman for Mr Kuchma, told the Associated Press that it would be analysed and studied in detail before any decision on further co-operation with London and Washington was taken.
Serious worry
The row erupted in September after the US authenticated a secret tape recording by Mr Kuchma's former bodyguard, Mykola Melnychenko, in which the president allegedly agreed to the sale.
The radar would upgrade Iraq's air defences, a serious worry for Britain and America as they plan a possible campaign against Iraq.
In September, the US suspended about $54m of aid for the Ukrainian Government, after saying that the tape was genuine.
US officials have suggested that the results of the investigation could lead to additional penalties being imposed.
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