The request from the Home Secretary is said to have come in response to a letter from the Chilean government asking for the former dictator to be sent back home on humanitarian grounds. The Chilean foreign minister, Juan Gabriel Valdes, wrote to Mr Straw saying the general was "in no condition to endure a long trial".
Yesterday, a spokesman for the Chilean foreign ministry confirmed Mr Straw had asked for General Pinochet to undergo medical tests.
Supporters of the 83-year-old general claim his health is deteriorating under the stress of his battle to avoid standing trial for human rights abuses. He is said to have suffered strokes, a heart condition, diabetes and depression.
General Pinochet was excused from attending last month's court hearing at which a magistrate ruled he should be sent to Spain as requested on the grounds that he was too frail.
That decision was taken on the basis of medical evidence from Surrey GP Michael Loxton, who told the court the general had suffered two strokes recently.
He has already undergone a series of medical tests at local hospitals, including a brain scan, as concern over his condition mounts among his supporters.