Bund futures dropped 72 ticks to 136.55 at the open, extending losses of more than a point seen on Monday as officials looked to be considering plans to boost the size of the euro zone's rescue fund.

European stock index futures pointed to significant gains, following on from a strong session in Asia.

But with no firm proposals on the table, and any significant changes to the European Financial Stability Facility subject to a lengthy approval process by member states, the appetite for safe-haven Bunds could return in the near term.

"There seems to be a bit more noise on plans ahead, but whether they get it through or not it another matter. It's a classic post-big EU conference rally, but the question is 'has it got legs beyond two or three days?," said a trader.

Technical analysis by PIA First showed momentum remained negative for Bunds, and a fresh buy signal would only emerge if the contract broke above 137.66 -- the peak of an intraday bounce seen on Monday. The Sept. 13 open at 136.13 offered the next technical support level, according to PIA First charts.

Later in the day, Italy will kick off a busy week of debt sales with short-term and zero coupon debt. The country will issue longer-term debt later this week in a more rigorous test of investor appetite for lower-rated euro zone paper.

Greek lawmakers are expected to approve a fresh property tax at a vote set for around 1600 GMT as the country continues to press ahead with austerity measures aimed at securing the next tranche of bailout funding it needs to avoid a default in October.