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By David Milliken
LONDON, Dec 17 (Reuters) - Britain's national statisticsagency proposed a revamp on Tuesday of how it presentspolitically sensitive public borrowing data, changes that couldadd more than 100 billion pounds ($163 billion) to how much thecountry officially owes.
Some of the alterations are due to new European Unionstatistical rules, which mean, for example, that thenot-for-profit body which operates Britain's rail network willbe classified as a public rather than a private corporation.
But others are part of an attempt to clean up how Britain'spublic accounts are presented after the financial crisis, whichsaw the purchase of big stakes in Royal Bank of Scotland and Lloyds Banking Group as well as over 375 billion pounds ofgovernment bond purchases by the Bank of England.
"The existing measures are no longer fit for guidance, nolonger fit for purpose," Iain Bell, a senior official at theOffice for National Statistics, told reporters as the ONSstarted a consultation into the proposed changes.
Many private-sector analysts and the government's budgetwatchdog already use a modified version of the ONS's headlinemeasure of the public finances which additionally strips outsome payments linked to BoE bond purchases and Royal MailGroup's historic pension assets and liabilities.
Credit ratings agencies prefer a separate measure, generalgovernment gross debt, which is more internationally comparable.
However, the ONS proposals go much further and raisequestions about how easy it will be to compare the new numberswith past government forecasts of how rapidly Britain's budgetdeficit and debt level are falling in the run-up to the May 2015national election.
Starting next September, the ONS plans to replace itscurrent headline measure - public sector net borrowing excludingfinancial sector interventions - with a new measure, publicsector net borrowing excluding public-sector banks.
The ONS said that the change - if implemented already -would add 112 billion pounds to Britain's public sector net debtfor the 2012/13 fiscal year, when it already stood at 1.182trillion pounds or 74 percent of gross domestic product.
Some 30 billion pounds of that increase is due to the changein classification of Network Rail, required by the EU.
Of the remainder, 24 billion pounds comes from a changedtreatment of the BoE's bond purchases and 58 billion pounds fromno longer counting the government's stakes in RBS and Lloyds andits payments into a bank bailout fund as liquid assets.
"When the guidance on the 'ex-measures' was firstestablished, government share-holdings of banks were notexpected to last as long as transpired," the ONS said.
The ONS said the effect of the changes on Britain's annualpublic sector net borrowing, which was 115 billion pounds or 7.3percent of GDP last year, would be smaller than on the debtlevel, and last year would have been equivalent to a reductionin the shortfall of 4 billion pounds.
The ONS said it would offer further details on the changesin February.
