Banks around the city are locking out ATM users at night in an effort to keep out homeless people — some of whom have been using the vestibules as toilets, sources tell The Post. Branches of Chase, City National Bank and Citizens have been quietly locking their doors even to customers who have a bank card as early as 10 or 11 p. m. and reopening them in the early morning, The Post has learned. Bank branch employees told The Post that ATM lobbies have become refuges for homeless people who sleep in them overnight or use the space as toilets, leaving “poop” behind and creating a safety hazard for both employees and customers who are afraid to enter the lobbies. “A lot of stuff happens at night,” said an ATM technician who did not want to be identified because he’s not authorized to speak to the media. He added that some banks, including Bank of America branches, “periodically” shut their ATM lobbies overnight. Bank of America did not respond for comment. Citizens acknowledged the disruption to its service, citing “safety issues. ” “Like a number of other banks, we have temporarily closed some ATM vestibules overnight at certain New York City branch locations where we have seen repeat activity that could present a potentially dangerous situation for our customers or colleagues,” spokesperson Eleni Garbis said in a statement. A spokesman for Chase, Jerry Dubrowski, said the situation is “fluid” and that the bank is “constantly evaluating the environment in a community. ” Some Chase branches may close for a period of time and then reopen for full 24-hour access again, he said, adding that the limited hours apply to a minority of Chase branches in the city. Some banks have hired security guards to sit inside the vestibules in the early evening hours, Matt Roberts, president of the 17th Precinct Community Council, told The Post, adding that some homeless people have bank cards and can let themselves into the lobbies. In April, The Post documented the homeless problem in ATM lobbies, including photos and accounts of a shirtless man sitting on the floor of a Bank of America surrounded by his belongings, others sprawled out on sleeping bags and a couple shooting up drugs. Earlier this year, banks began to put pressure on the NYPD to remove people from the lobbies, according to Roberts, whose precinct covers Midtown East neighborhoods including Murray Hill and Sutton Place. But after a March incident in which two NYPD officers were attacked by a homeless man at a Citibank branch on Park Avenue when they asked him to leave the lobby, Roberts called on the banks to simply lock their doors overnight. Roberts is bracing for the issue to become a bigger problem when lower temperatures arrive and the “city is kicking people out of the subways,” he told The Post. In the meantime, several banks are heeding his advice and simply locking their doors overnight, including the Chase branch at 1120 Sixth Ave. , which closes its ATM lobby at 10 p. m. and reopens it at 7 a. m. The nearby City National Bank branch closes its ATM lobby at 11 p. m. , reopening it at 6 a. m. City National did not respond for comment. “Unfortunately the private customers of ATM systems during off hours will be the collateral damage,” Roberts said. .