* FTSE 100 down 0.3 percent
* Banks hurt by renewed jitters over euro zone debt
* Retailers knocked by worries over outlook
By Tricia Wright
LONDON, Feb 11 (Reuters) - Weak banks pushed Britain's top share index into negative territory on Friday, pressured by renewed concerns over European sovereign debt, while retailers were hit by worries about pain ahead on the high street.
By 0936 GMT, the FTSE 100 index was down 16.64 points, or 0.3 percent, at 6,003.37, after it closed down 0.5 percent at 6,020.01 on Thursday.
Banks extended their decline from the previous session when the mood was darkened once again by sovereign debt fears, after Portugal's government bond spreads widened.
Portugal is seen by many economists as the next likely country that will need a bailout in the euro zone after Greece and Ireland, but the government insists it needs no foreign aid.
"The banks are the biggest drag on the FTSE this morning on concern about the sovereign debt situation and Portuguese bond yields," Michael Hewson, market analyst at CMC Markets, said.
Barclays, scheduled to report full-year results on Tuesday, was the worst off, shedding 1.2 percent.
"Barclays have had a decent run prior to the results coming out, and when they do come out, there could be limited upside," Manoj Ladwa, senior trader at ETX Capital, said.
Elsewhere among financials, Legal & General grabbed the top spot on the blue chip leader board as Nomura lifted its price target for the life insurer to 171 pence from 150.
"We think the market is underestimating the growth potential of L&G's asset management operations," the broker said in a note.
HIGH STREET GLOOM
Retailers were weak, with Next and Marks & Spencer among the top FTSE 100 fallers, off 2.9 percent and 2 percent respectively, with analysts suggesting the latest weekly department store sales figures from John Lewis underwhelmed.
"The department store chain has started to struggle a little in the last few weeks against tough comparatives," Arden Partners analyst Nick Bubb said.
"We can be sure that life will be much tougher elsewhere on the High Street, as John Lewis is likely to be still outperforming the general non-food market," he said.
British manufacturers' input costs rose at their fastest annual rate in more than two years in January, led by sharp increases in the cost of oil and imported metals and materials, official data showed.
Miners helped limit the FTSE 100's falls, recovering after falls in the previous session.
The market was keeping a close eye on developments in Egypt, after President Hosni Mubarak said he would not step down immediately in a speech which did little to inspire confidence in a quick solution to the Egyptian crisis.
Technical factors remained cautious for the FTSE 100 index.
"The weak close (on Thursday) has put the index in a position to weaken further," James Hyerczyk, an analyst at Autochartist, said.
"The key number to watch is 5,997.38 which is last week's close. Finishing under this level will form a weekly closing price reversal that could lead to the start of a two- to three-week correction," Hyerczyk added. (Editing by Hans Peters)