The demonstrators are organizing a sit-in, refusing to leave until Minister Mohammad Mashnuq resigns.
Security forces have sealed off all entrances to the ministry building, according to The Daily Star.
The protesters are part of the “You Stink” campaign, which has given the government until Tuesday evening to meet its demands.
Those demands include a sustainable solution to a trash crisis that flared in mid-July, the resignation of Mashnuq, and new elections to replace a parliament that has been in power since 2009, AFP reported.
The action on Tuesday comes just two days after the movement promised a “surprise” for the government.
“You Stink” organized a huge demonstration in central Beirut on Saturday, threatening to escalate its efforts if the government did not meet its demands by Tuesday evening.
Tens of thousands of people gathered in Beirut’s Martyrs Square, chanting “The people want the downfall of the government!” and “Revolution!”
They expressed anger at government corruption and a lack of basic services, including power and water.
The movement was initially launched to demand a solution to the garbage crisis, which has seen trash pile up uncollected. It has since expanded to a call for a total government rehaul.
Lebanon has seen a series of protests against the government, prompted by the country’s waste crisis.
Demonstrations have so far been mostly peaceful, although 10 people were arrested and two policemen injured in clashes between officers and protesters on Sunday, according to security officials.
The “You Stink” movement has tried to distance itself from those involved in violent clashes with police.