By Hideyuki Sano and Nichola Saminather
TOKYO/SINGAPORE (Reuters) - Asian shares pulled back on Friday as investors sought refuge in safe-haven assets amid festering concerns over the June 23 referendum that could see Britain exit the European Union.
MSCI's broadest index of Asia-Pacific shares outside Japan (MIAPJ0000PUS) dipped 0.6 percent, but remains poised for a weekly gain of 1.7 percent.
Japan's Nikkei (N225) declined 0.5 percent, extending losses for the week to 0.3 percent.
China's CSI 300 index <.CSI300> slipped 0.4 percent, and the Shanghai Composite <.SSEC> retreated 0.3 percent, setting them up for falls of 0.8 percent and 0.4 percent respectively.
Hong Kong's Hang Seng index (HSI) slipped 0.3 percent, heading for a loss of 1.4 percent for the week.
"There are concerns over 'Brexit' as polls seem to suggest the probability of Britain leaving Europe is rising," said Tatsushi Maeno, managing director at PineBridge Investments.
"You can't buy risk assets under such conditions even if you want to," he said.
Wall Street shares also pulled back on Thursday after three days of gains, as a decline in the number of unemployment benefits claims last week showed the labour market remains strong despite May's unexpected drop in job growth.
The S&P 500 (SPX) lost 0.17 percent to finish at 2,115.48, but remained only about 15 points below its record closing high.
Global bond yields dropped to new lows and perceived safe-haven currencies gained as investors fled to the safety of bonds on concerns about Britain's referendum on European Union membership on June 23.
"There are a number of different factors driving yields lower and it started last week with the weak U.S. jobs data pushing rate-hike expectations back," said Patrick Jacq, European rate strategist at BNP Paribas (PA:BNPP).
"For the euro zone, this was the only constraining factor for lower yields."
German 10-year Bunds yield hit a record low of 0.023 percent (DE10YT=RR) while the 10-year British gilt yield (GB10YT=RR) struck an all-time low of 1.222 percent.
The start of the European Central Bank's corporate bond purchase programme also bolstered European bonds.
In Japan, the 10-year government bond yield
The 10-year U.S. Treasuries yield (US10YT=RR) broke out of the trading range is has been in since March to hit a 3 1/2-month low of 1.659 percent on Thursday. It last stood at 1.6798 percent.
The retreat in risk sentiment is proving a boon for gold, which is hovering near a three-week high, and on track for a second straight weekly rise.
Spot gold
In the currency market, the decline in U.S. unemployment benefit claims supported the dollar index, which tracks the greenback against a basket of six peers. The index (DXY) advanced 0.3 percent, extending gains for the week to 0.2 percent.
The Swiss franc has gained 1.6 percent over the past five days, its biggest five-day gain since March 2015, hitting a eight-week high of 1.0886 franc per euro (EURCHF=EBS) on Thursday. It last stood at 1.08980, on track for a weekly increase of 1.8 percent.
The low-yielding yen
The euro
The British pound
Although it has stayed 4.5 percent above its seven-year low set in late February, investors are actively seeking protection against a slide in the event of Brexit.
The cost of hedging against swings in sterling's exchange rate over the next month soared, with sterling's one-month implied volatility
Oil prices also stepped back after notching another 2016 high.
Still, persistent threats by militants against Nigeria's oil industry and fear of more security incidents that could hit supply limited losses in crude.
Global benchmark Brent crude futures (LCOc1) slipped 0.1 percent to $51.88 per barrel, after having risen to as high as $52.86 on Thursday, and looks set to record a 4.5 percent gain for the week.
U.S. crude (CLc1) slid 0.2 percent to $50.44 a barrel, poised to end the week 3.7 percent higher.
