The head of an agency may detail, for a period of not more than 5 years, an employee of his agency to an international organization which requests services, except that under special circumstances, where the President determines it to be in the national interest, he may extend the 5-year period for up to an additional 3 years.

An employee detailed under subsection (b) of this section is deemed, for the purpose of preserving his allowances, privileges, rights, seniority, and other benefits, an employee of the agency from which detailed, and he is entitled to pay, allowances, and benefits from funds available to that agency. The authorization and payment of these allowances and other benefits from appropriations available therefor is deemed to comply with section 5536 of this title.

An employee detailed under subsection (b) of this section may be paid or reimbursed by an international organization for allowances or expenses incurred in the performance of duties required by the detail, without regard to section 209 of title 18.