The UK should not agree to a US deal to buy the F-35 Joint Strike Fighter unless the US releases details allowing independent operation, MPs have warned.
Britain is expected to take 138 Joint Strike Fighter aircraft
The defence committee said an assurance was needed from the US "by the end of the year" that all the technical information would be given to the UK.
The $276.5bn (£140bn) Anglo-US project will supply the armed forces of the US, Britain and several other countries.
Earlier this year, the government expressed concerns about the deal.
The F-35 Joint Strike Fighter, the world's most expensive military project, is expected to take to the skies for its maiden test flight next week.
The US will account for the lion's share of the Lockheed Martin-designed plane, with 2,400 in service by 2027, while the UK is expected to take delivery of 138 fighters.
Britain's BAE Systems is one of the key players in the aircraft's development, and has pumped $2bn into the project.
The Ministry of Defence is planning to get a variation of the JSF for use by the Royal Navy on two future aircraft carriers.
It still remains unclear whether the US will agree to transfer the technology required to give the UK operational sovereignty of the aircraft.
The committee said if there is no deal by the end of the year, the government should focus on developing a "plan B" to acquire alternative aircraft.
Shadow defence minister Gerald Howarth said the Conservatives had endorsed the government's call for the transfer of the technology to the UK.
In its report published on Friday, the MPs also highlighted the equipment urgently needed by UK Forces in Afghanistan and Iraq.
They welcomed Prime Minister Tony Blair's promise in October that forces would get whatever resources they asked for.
They urged the MoD to process such requests quickly and the Treasury to approve additional funding "to support new equipment once in service, so that commanders are not inhibited from asking for equipment by fears for their future budgets".
They were particularly concerned about £205m spent on eight Chinook Mk3 helicopters, housed in hangars but not being used - " possibly until the next decade, while the MoD negotiates with Boeing about responsibility for solving a software problem".
Mr Howarth said: "The report reiterates some of the serious concerns we have with the government's procurement policy, particularly highlighting the delays affecting some major projects and the cutting of equipment numbers to control costs.
"The government has failed to deliver the essential equipment needed by our Armed Forces when Britain's military commitments are increasing."
F-35 JOINT STRIKE FIGHTER
The JSF is a supersonic stealth aircraft
Built to replace F-16s, F/A-18 Hornets and Harriers
Each plane costs approximately $45m
Variations include one for aircraft carriers and a jump-jet
Possible weapons are 'smart' bombs, air-to-air missiles and the UK's Storm Shadow cruise missile