An outage at news and market data provider Bloomberg LP hit financial markets around the world today, prompting debt sales to be postponed and exacerbating a spike in volatility in European stocks. 

Service was restored to most customers later during the day.

The lack of price visibility was blamed for accelerating a sell-off in European shares, while trading volumes in German government bond futures contracts fell by around a third. 

Social media first reported the Bloomberg systems going down at around 6.20am and the screens were blank for most of the following two hours, market participants said, adding that prices were unavailable and the news feed intermittent. 

It was unclear what caused the outage on the system that provides real-time news and financial information to more than 320,000 subscribers globally and allows users to trade across asset classes. The impact was widely felt. 

Bloomberg News, which has 2,400 reporters and editors in more than 150 bureaus worldwide, competes with Thomson Reuters in providing financial news and information. 

"Significant but not all parts of our system experienced a disruption today. There is no indication at this point that this is anything other than an internal network issue. We have restored service to most customers and are making progress in bringing all parts of the system back online," Bloomberg said in a statement. 

Britain's Debt Management Office had planned a regular sale of £3 billion of treasury bills this morning. The tender was rescheduled this afternoon. 

The DMO said the postponement would not cause any funding issues for the UK Treasury. A spokesman said he could not recall the agency ever having to postpone a sale in similar circumstances. 

The Bank of England said its core operations were not affected and that it had "all the tools it needs to carry out its responsibilities for financial stability, and provision of market liquidity, if and as required." 

In a statement, Britain's financial market regulator The Financial Conduct Authority said: "We are aware of the issue and are monitoring the impact on our firms." 

Traders said the length of time the Bloomberg screens were down was unprecedented.

The volume of trading in German Bund futures in early trade was down by around a third compared with the same period in the last few Friday trading sessions.

In a two-hour period, 62,845 lots of Bund futures were traded, according to Eurex data. That compares with 96,301 contracts a week ago, 89,048 on March 27 and 88,476 on March 20. 

Bankers told Thomson Reuters market news service IFR that at least one corporate bond sale worth over €1 billion had been delayed because of the outage.

Traders said the outage had exacerbated volatile activity on stock markets, particularly around the expiration of options contracts. It also hindered the ability of traders to react to the announcement of new Chinese regulations.