WASHINGTON — For the next week the federal government will pay all of the costs to help get public transportation and power restored to parts of New York and New Jersey hit hardest by Superstorm Sandy, the Federal Emergency Management Agency said Thursday.

FEMA Administrator Craig Fugate said President Barack Obama has approved requests from New Jersey and New York for the government to cover the costs for emergency transportation, including helping repair subway tunnels and get buses running, and power grid repairs for 10 days. He did not give any estimates of how much that could cost.

The president’s decision does not mean that the government will eventually reimburse the states for all the costs to repair damage from the massive storm that plunged parts of Manhattan into darkness, shut down much of the subway and destroyed parts of the New Jersey shore.

Fugate said FEMA generally pays states back for 75 percent of repair and recovery costs. In some cases, the agency has covered as much as 90 percent of disasters costs.

But Fugate said it’s too early to know how much of the costs the government may eventually cover.

“What will be needed later, as far as cost share adjustments, will be made later,” Fugate said.

Officials from both states have asked that the government reimburse the local governments for all of the costs.

Insurance companies have estimated that the storm could cost them anywhere from $10 billion to $20 billion. According to the forecasting firm Eqecat, total economic damage could run as high as $50 billion.