Greek riot police clashed with dozens of police unionists in Athens who were Thursday preventing them from boarding buses bound for Thessalonki to put down anti-government protests.

The brief clashes took place outside the police academy just as hundreds of riot police gathered to depart for the northern port ahead of Saturday’s speech on the economy by Prime Minister Antonis Samaras to mark the opening of the International Trade Fair.

Police, fire-fighters and coast guard officers were planning further demonstrations in Athens later Thursday against a fresh round of public sector pay cuts as part of a massive new austerity package needed for Greece to continue receiving bailout loan instalments.

Samaras is struggling to get his coalition partners to back 11.5 billion euros (14.4 billion dollars) in austerity cuts for 2013-14.

The premier is also rushing to have the package ready in line with commitments to the European Commission, European Central Bank and the International Monetary Fund, the so-called troika.

Troika officials will launch talks with the government on Friday and will meet with Samaras on Monday. A meeting scheduled between Samaras and his coalition partners on Thursday to discuss the package was cancelled.

The troika, which has been keeping the country solvent with rescue loans since 2010, will then decide whether to release the next bailout payment of 31.5 billion euros. Without the money, Greece will be forced to default on its debt.