An angry crowd of around 1,000 Bulgarian demonstrators, some throwing eggs and tomatoes, blockaded parliament on Wednesday in a 13th straight day of anti-government protests.
Because only 112 out of 240 lawmakers braved it through the protesters who were shouting "Mafia!" and "Resignation!" outside the parliament building in central Sofia, the session was cancelled.
Deputy parliamentary speaker and Socialist party lawmaker Maya Manolova was pelted with missiles after trying to address the angry crowd, who then prevented MPs from leaving even after the session was scrapped.
"This instability can continue indefinitely, I am afraid. Of course, we will not be able to work without parliament," Prime Minister Plamen Oresharski told journalists on leaving the legislature escorted by police.
Between 7,000 and 10,000 people have protested every evening since June 14 in the European Union's poorest country after the controversial appointment of a media mogul as head of a powerful security agency.
This move, angering people fed up with corruption and cronyism, has since been withdrawn but the protests have turned into demonstrations against the government and politicians in general.
In February mass protests prompted the previous right-wing government of Boyko Borisov to resign. Elections in May were inconclusive and the non-partisan Oresharski was named premier of a Socialist-backed administration.
The Socialists and their partners, the Turkish minority MRF party, have 120 MPs.
But in order to function, parliament needs the presence of at least one more lawmaker from the unpredictable ultra nationalist formation Ataka, who failed to show up on Wednesday.
Borisov's opposition conservative GERB party has boycotted parliamentary sessions since last week.
"If Ataka refuses to take part in the work of parliament, this will change the situation towards snap elections," Socialist party leader Sergey Stanishev said Wednesday.