Occupy Wall Street protesters are suspected of sending envelopes containing white powder that arrived in the mail at seven locations throughout Manhattan on Monday afternoon, police said.

The mailings targeted six banks and a city-owned office building at 100 Gold St., where the mayor’s mail is processed.

Some of the envelopes, including one addressed to Mayor Bloomberg, also contained a letter that investigators believe referred to the movement’s plans to bring Manhattan traffic to a standstill with a series of protests for May Day Tuesday, police said.

“This is a reminder that you are not in control. Just in case you needed some incentive to stop working. We have a little surprise for you,” the angry letter read, according to an email from NYPD Deputy Commissioner Paul Browne.

Protesters plan to gather in front of banks, clog downtown streets and impede traffic in tunnels and the Brooklyn Bridge, where 700 demonstrators were arrested for blocking off the span last fall.

Occupy organizers said Tuesday’s demonstrations are intended to turn the annual celebration of organized labor into a protest against the poor job market and gender discrimination in hiring.

“We have another world at our fingertips,” said organizer Marisa Holmes at Zuccotti Park, where the movement was born. “And it’s up to us to make it happen.”

An Occupy-related website included a call for people to join in the May Day protests.

“No work, no school, no shopping, no housework, no compliance,” the posting read. “If you can’t strike, call in sick. If you can’t call in sick, hold a slowdown.”

The contents of four of the letters were found to be harmless; three were still being tested Monday night, police said.

Police sources expect the Transport Workers Union and Local 1199 to hold peaceful rallies Tuesday.

Meanwhile, four City Council members have demanded a federal monitor for the NYPD because of alleged police brutality at previous Occupy Wall Street protests.

(Source: NY Daily News)