WASHINGTON  A provision buried deep inside the $787 billion economic stimulus bill would impose restrictions on executive bonuses at financial institutions that are much tougher than those proposed 10 days ago by the Treasury Department.

The provision, inserted by Senate Democrats over the objections of the Obama administration, is aimed at companies that have received financial bailout funds. It would prohibit cash bonuses and almost all other incentive compensation for the five most senior officers and the 20 highest-paid executives at large companies that receive money under the Treasury’s Troubled Asset Relief Program, or TARP.

The stimulus package was approved by the House on Friday, then by the Senate in the late evening.

The pay restrictions resemble those that the Treasury Department announced this month, but are likely to ensnare more executives at many more companies and also to cut more deeply into the bonuses that often account for the bulk of annual pay.

The restriction with the most bite would bar top executives from receiving bonuses exceeding one-third of their annual pay. Any bonus would have to be in the form of long-term incentives, like restricted stock, which could not be cashed out until the TARP money was repaid in full.