The eurozone debt crisis is about to enter a dangerous phase as governments prepare to step up borrowing in the capital markets to fund their faltering economies.

Eurozone governments will attempt to issue double the amount of debt this month compared with August, with some strategists warning that some of the weaker economies could fail to raise the amount of money they need.

Spain, Portugal and Ireland, the so-called peripheral eurozone economies, are considered most in danger of being shunned by investors as worries persist over the health of their banks and economies. Greece is no longer a concern as it has emergency loans to cover its funding for the next two years.

Padhraic Garvey, head of rates strategy for developed markets at ING Financial Markets, said: “We are heading into a critical period as the chances rise that a government may fail to raise the money it needs.

“Spain, Portugal and Ireland are the obvious ones to worry about. Are investors willing to stay long, or buy the debt of these countries? I’m still not seeing investors willing to buy into the periphery.”

Eurozone governments will try to raise €80bn in September compared with new bond issuance of €43bn in August. Spain is expected to attempt to borrow €7bn in September compared with €3.5bn in August, according to ING Financial Markets.

Other strategists, however, insist governments will have little difficulty in funding themselves, even if they have to pay higher premiums or yields to attract investors.

They point to the fact that countries such as Portugal and Ireland have already raised most of the money they need to fund themselves this year.

Yet, government bond yields of the peripherals may come under further selling pressure. Yield spreads against Germany, the eurozone’s benchmark economy, could also widen. Last Tuesday, Ireland saw the extra premium it has to pay over Germany jump to a record 356 basis points.