(Updates with close of the stock market)
NAIROBI/LONDON, Sept 1 (Reuters) - Kenya's shares and dollar bonds plummeted on Friday and its currency fell after the countrys Supreme Court declared President Uhuru Kenyatta's election victory invalid.
Analysts said the ruling signalled new uncertainty for East Africas most developed economy. Another vote must be held within 60 days, according to the constitution.
The main stock index, the NSE-20, dropped 3.5 percent to close at 3887.28 points, data from the Nairobi Securities Exchange showed.
In London one Africa economist, John Ashbourne at Capital Economics, cited the risk of a violent reaction.
President Uhuru Kenyatta said he disagreed with a Supreme Court ruling that nullified his win in last month's presidential election, but that he would respect the decision and urged citizens to do the same.
There were also no signs of tension in Kenyatta's ethnic strongholds, while supporters of opposition leader Raila Odinga celebrated peacefully in the streets in areas that had voted for him.
The stock exchange halted trading briefly midway through the session after blue-chip shares plummeted.
Trading resumed at 1000 GMT, exchange Chief Executive Geoffrey Odundo told Reuters. He said shares had fallen by the maximum daily limit of 10 percent, which requires a trading halt.
Telecoms operator Safaricom, the biggest company by market value, fell nearly 5 percent to close at 24.25 shillings ($0.2351) per share, traders said.
"No one likes uncertainty, especially if the uncertainty period is as long as 60 days," said Ken Minjire, head of securities at Nairobi-based Genghis Capital.
The Kenyan currency, the shilling, partly recovered after an early slump to trade at 103.10/20 per dollar, down around 0.4 percent from Thursday's close of 102.75/95.
Kenya's $2 billion sovereign bond maturing in 2024 fell 1.33 cents, according to Tradeweb data, its lowest since mid-August. The 2019 issue fell 0.75 cents to 102.75 cents.
Kenya's average yield premium over Treasuries blew out 25 basis points (bps) on the EMBI Global Diversified index to 411 bps. The underlying emerging debt index was unchanged.
"People will be looking at the tone the president takes," Ashbourne added.
Kenya has a history of disputed elections. A row over the 2007 poll, in which Odinga also lost out, was followed by weeks of ethnic bloodshed in which more than 1,200 were killed. ($1 = 103.1500 Kenyan shillings) (Additional reporting by Alexander Winning and John Ndiso; editing by Larry King)