According to local media, the occupations began in the early hours of Thursday and will continue until Friday.
The protesters are opposing a new round of pay-cuts and layoffs imposed by the government and aimed at slashing its runaway deficit.
The protesters say they want to prevent the Greek Finance Minister from meeting the EU, the IMF, and the European Central Bank officials in Athens.
Thousands of protestors gathered outside the Parliament, expressing their anger at the MPs.
The police officers who came to the streets demonstrated on their payday against the government's austerity measures.
“We are demonstrating against the economical measures of the government because next month with the salary we [get], we will not be able to live, we will get a 400 euro salary, with this money we can't do anything, we can't help our family,” the general secretary of the police union, Ylannis Fanariotis told Press TV.
The policemen left their belts to their colleagues guarding the Parliament in a symbolic move and handed a resolution along with their demands to the president of the Parliament .
On Tuesday, more than 165,000 demonstrators took part in over 100 nationwide protests, the Associated Press reported.
The public voiced outrage at French President Nicolas Sarkozy's government, which has shed tens of thousands of education-related positions since 2007 and plans to rid a further 14,000 in 2012.
The measures have caused schools to run into training problems and staff shortages.
- "If you go back to the savings and loan debacle, we got more than a thousand felony convictions of the elite. These are not, you know, tellers or something. We today have zero convictions, zero indictments, zero arrests of any of the elite, non-prime lenders that, through their fraud, drove this crisis."