There are reports of unprecedented civil disorder in Uzbekistan, where several thousand people have taken to the streets in the city of Kokand.
By Monica Whitlock
BBC correspondent in Tashkent
Eyewitnesses said that protesters threw stones and torched police cars after the government brought in new restrictions on trade.
Thousands filled the main bazaar, shouting angrily against the new laws.
The Uzbek government rules with an iron grip, but ordinary Uzbeks are increasingly challenging its authority.
Protesters set two police cars on fire and stoned the tax office nearby, smashing the windows.
One eyewitness reported that the city's mayor climbed on a market stall to address the crowd but he was drowned out by furious protesters.
A column of marchers then set off towards the government office in the city centre.
Local police confirmed that a large protest was going on. They said their officers were standing by to contain the situation and had not been armed.
The demonstration was sparked by a law that puts new restrictions on trade, already very difficult in Uzbekistan.
From now on it will be illegal for traders to use intermediaries. If traders buy goods abroad, they must sell them personally without going through any other retailer. Each trader must also have a special government licence.
The authorities say these measures will keep prices down, but people here say tens of thousands of businesses will collapse.
It is very hard to judge the numbers involved in the Kokand protest.
Early reports spoke of as many as 20,000, but the hard core seems more likely to be 2-3,000.
Even a conservative figure means this protest is far bigger than any seen in Uzbekistan in recent years.