A top Bush administration official on Thursday defended the vetting process the government uses to review foreign takeovers of companies on national security grounds, and signalled that attempts by Congress to overhaul the process could pose “constitutional” issues.

Robert Kimmitt, deputy Treasury secretary, said he believed the committee on foreign investments in the US (CFIUS) a 12-member inter-agency panel chaired by the Treasury was “sufficiently flexible” to protect national security assets.