A stable but lacklustre economic outlook will push the European Central Bank to tweak its asset purchase programme and announce an extension by year-end.

However economists polled by Reuters said a move was unlikely later this week. 

The ECB has spent over €1 trillion buying government bonds, cut its refinancing rate to zero and adopted a negative deposit rate.

This is besides giving billions of euros in essentially free loans to commercial banks to lend on to customers. 

But inflation, which the ECB targets at close to but just below 2%, has often dipped below zero in the past couple of years due to weak energy prices, tepid demand from consumers and businesses, and high unemployment in several top economies.

The outlook for prices remained weak in the latest survey and not a single forecaster, in the sample of over 60, had a 2% inflation call anywhere over the next year and a half. Inflation stood at 0.4% in September, according to early data. 

Over 90% of the economists in the poll (conducted over the past week) who had a view on what the ECB would likely do by the end of the year, picked an extension to the QE programme beyond March 2017 as the most likely option. 

Almost half of them said some changes in the technical parameters of QE was probable too. 

At its meeting on October 20, the ECB is expected to hold monetary policy steady. 

A move by ECB President Mario Draghi at the December 8 meeting could help multiply the impact of the stimulus on the euro's exchange rate, especially since the US Federal Reserve is widely expected to hike rates a week later, boosting the dollar. 

The wider poll showed the currency bloc will maintain its current 0.3% quarterly growth pace for the rest of 2016, after a surprisingly robust start to the year.

The pace of growth next year will be stymied by a slight slowdown in its number one and two economies, Germany and France, which are expected to expand 1.4% and 1.2% respectively. 

The outlook has improved a little for peripheral economies such as Greece, which is now expected to contract less than earlier thought, and Portugal where growth will likely be stable this year and next.

By its own rules, the ECB can only buy debt that yields more than its -0.4% deposit rate and restrictions apply on the amount of debt it can buy of a particular country as well as the composition of assets it purchases. 

But a steep-fall in global bond yields this year has meant the ECB is running out of sovereign debt to buy and it needs to tweak its own rules to ensure its QE programme continues to run. 

A few economists said the ECB could expand its monthly QE amount from the current €80 billion. Only one forecaster said the ECB would announce a tapering of QE from March or a future date.