Greece's Prime Minister George Papandreou has called an emergency cabinet meeting for this afternoon as speculation mounts the country's government is about to collapse.
Overnight the Greek PM stunned markets after announcing a referendum in Greece about whether to accept the terms of the eurozone bailout.
His position at the helm is now under a renewed threat, with the Guardian reporting six MPs have so far called for his resignation.
Papandreou and the ruling party are at risk of losing the working majority in the 300-seat House, according to the report.
"It's all over. The government is about to collapse," an official told the newspaper.
Markets saw heavy losses following the latest twist in the Greek debacle.
US shares followed the trend set by European peers by racking up losses at opening, with both the Dow Jones and S&P 500 off sharply.
The Dow is down 1.5%, extending yesterday's losses to leave the index at 11,774 points. The S&P 500 is also off 1.7%, at 1,232.
In the UK losses were also mounting, with the FTSE 100 down 2.5%, although off day lows, at 5,407 points.
European shares were also lower, with the German Dax down 4% at 5,894, and the French Cac 40 off 4.9% at 3,085.
Banks were among the worst affected stocks across Europe and the UK.
Barclays was off 7.9%, Lloyds has shed 4.9%, and RBS was 6.2% lower, while HSBC was down 2.4%.
In Europe Societe Generale had plunged 15%, BNP Paribas was down 11% and the National Bank of Greece was off 23%.
In Germany, banking giant Deutsche Bank plummeted 17.9%.
Two global vehicles
'Further plug advice gap'
Must appoint separate CEOs and boards
Advisers do come out well
Will report to Mark Till