The Lebanese prime minister's political party has called for his return from Saudi Arabia after his dramatic resignation, fuelling speculation the kingdom is holding him against his will.

Saad Hariri shocked his country on Saturday when he announced in a televised statement out of Saudi Arabia that he was stepping down. He has not been seen in Lebanon since.

Mr Hariri’s Future Movement party issued a statement on Thursday evening saying it was "necessary" for the politician to return "to restore Lebanon's dignity and respect."

The small state of Lebanon is used to affronts to its sovereignty, often becoming a battleground for proxy conflicts in the region, but it has not seen anything like the spectacle that has played out in the last few days.