Lawmakers said Monday they have secured a commitment by U.S. Customs to keep 24-hour staffing for a few more weeks at some northern Maine border crossings with Canada.

In a bid to tighten security, the U.S. government had said it would close and lock gates after hours at ports of entry at Hamlin, Easton, Monticello and Orient in Aroostook County and Forest City in Washington County.

Hours of operation essentially would remain unchanged. But the restrictions would limit the ability of U.S. residents to use special passes to enter the country after hours.

The new security measures were to have begun March 15.

U.S. Sens. Olympia J. Snowe and Susan M. Collins announced Monday evening that U.S. Customs has agreed to maintain 24-hour staffing at Hamlin, Easton and Monticello through the end of March, with an additional extension for Forest City and Orient through Memorial Day.

The newly renamed U.S. Customs and Border Protection Service has installed gates, security cameras and lights at the five ports of entry. A remotely monitored inspection system already has been suspended, but pass holders have been able to present their pass cards to border inspectors after hours.

Most ports will be open from 8 a.m. to 4 p.m. Orient will be open from 6 a.m. to 10 p.m. during the summer. Hamlin will be open from 7 a.m. to 11 p.m. seven days a week.

When the gates are closed, U.S. travelers will have to use 24-hour ports at Van Buren, Fort Fairfield, Bridgewater, Houlton or Vanceboro. The distance to those ports could add as much as an hour in travel time for some.

The effect on Canadian residents who want to return home after the gates are closed has not yet been decided.

The new safety measures were put in place as part of tightened border security stemming from the Sept. 11, 2001, terrorist attacks. The remote ports have been staffed 24 hours a day.