The EU's most senior finance officials will warn ministers this week about the threat of a renewed credit crunch as a systemic crisis in sovereign debt spills over to banks, according to EU documents.

In one a series of bluntly worded reports prepared by officials for a meeting of EU ministers on Sep. 16 and 17, they warn: While tensions in sovereign debt markets have intensified and bank funding risks have increased over the summer, contagion has spread across markets and countries and the crisis has become systemic.

This highlights a risk of a vicious circle between sovereign debt, bank funding and negative growth.

In the documents, the influential Economic and Financial Committee, which prepares the agenda for discussion among ministers, levels harsh criticism at countries including Spain for not doing enough to reinforce its banks following dismal results in stress tests.

One of the reports, dated Sep. 13, cautions that the spill-over effects could feed a dangerous negative loop between the financial and the real sectors (of the economy), whereby funding problems and ... risk aversion ... may lead to ... deleveraging by banks, thereby generating a credit crunch, in some Member States.

Outlining what they describe as spreading contagion and a sovereign debt crisis which they say has entered a new phase, officials highlight the difficulties experienced by European banks in borrowing.

Despite the considerable strengthening of capital positions compared to the levels of 2008-2009, European banks have recently experienced market funding difficulties resulting amongst others from stress on wholesale liquidity markets, high spreads in secondary markets, and, for some EU banks, growing difficulties in accessing funding from U.S. counterparties, one of the reports says.

To counteract dwindling confidence in EU banks, officials recommend to ministers that a further reinforcement of bank resources is advisable at this juncture.

They criticize some countries for not taking such measures -- which would include state-backed capital injections in flagging lenders -- after recent stress tests.

This is important for banks that have failed the stress test, but also for those that have passed the test but with capital levels close to the relevant threshold.

(Reporting by John O'Donnell; Editing by Ruth Pitchford)