A Chequer-Board of Nights and Days

We'll see where this story goes. It could be the catalyst for positive change. It could augur a bloody period. No one knows for sure what will happen and that is the most nervewracking part of it all:

At least one petrol station has been set on fire in the Iranian capital, Tehran, after the government announced fuel rationing for private motorists.

Iranians were given only two hours' notice of the move that limits private drivers to 100 litres of fuel a month.

Despite its huge energy reserves Iran lacks refining capacity, forcing it to import about 40% of its petrol.

Tehran is trying to rein in fuel consumption over fears of possible UN sanctions over its nuclear programme.

Iran fears the West could sanction its petrol imports and cripple its economy.

The restrictions began at midnight local time on Wednesday (2030 GMT Tuesday).

The BBC's Frances Harrison in Tehran says there is anger and frustration the government did not give people more notice.