Massive general strikes by the Greek public sector will all but paralyse much of the country as Greek trade unions launch another 24-hour general protest against planned additional austerity measures.

Transport services, including international trains linking Greece with Bulgaria and Romania, as well as shipping and domestic flights, are expected to be severely disrupted or cancelled. According to Bulgarian media, some, if not all Bulgarian and Greek border crossing points, might be temporarily closed for traffic, causing additional concern for those who need to travel.

Greece's main civil service and public sector unions say they represent about 2.5 million workers, while according to local media, organisers say that they hope more than 100 000 people will join the protests. Although most protesters are believed to be legitimate protesters, authorities fear that a hardcore, anarchist element could participate, prompting fears of renewed violence after a strike in Athens two weeks ago led to the deaths of three people in a bank blaze.

Greeks are angered by spending cuts and tax and pension-age rises planned in return for a 110 billion euro emergency bail-out - a measure designed to curtail debt and spending - and fresh budget cuts of 30 billion euro over three years.

Greece's current public deficit, which is worse than the 12.7 per cent initially thought, and stands at 13.6 per cent, is supposed to be cut down to three per cent in three years.

The strike will close government buildings, schools, banks, and reduce hospitals to an emergency skeleton staff.

It was confirmed by the Bulgarian state rail company BDZ that the protests will result in major disruption to traffic between the two countries. Four international trains, two in the morning and two in the afternoon on May 20 between Sofia and Thessaloníki, will be cancelled.

"All passengers who lost their tickets for the international trains will be reimbursed by BDZ," the statement said. Passengers will be able to receive their money back in full or reschedule for another date.

In spite of wide public opposition, including protests and violence that turned deadly, the rescue package for Athens from the European Union and the International Monetary Fund was agreed earlier in May as part of tough new austerity measures to help Greece curb its soaring debt and deficit.

Because of the turmoil in the Balkan state, the European single currency fell to its lowest level against the dollar since 2006, amid concerns that debt problems will undermine Europe's recovery from the global economic crunch.