FRANKFURT- The European Central Bank increased its emergency bond purchases by a third last week but a record amount of expiring debt leaving its balance sheet blunted the impact of the newly minted cash, ECB data showed on Tuesday.

The ECB pledged last month to speed up its Pandemic Emergency Purchase Programme (PEPP) to keep credit cheap for a euro zone economy still struggling with the consequences of the COVID-19 pandemic.

But it has failed to impress market participants so far, as its new purchases are often offset by maturing bonds bought in the spring of 2020, when the pace of PEPP was at its highest.

A record 12.1 billion euros of bonds bought under PEPP matured in the five days to April 16, effectively negating nearly half of the central bank's fresh purchases worth 28.4 billion euros, the ECB's weekly statement showed.

The euro zone's central bank is expected to stick to its ultra-easy policy stance at a meeting on Thursday but ECB President Christine Lagarde is certain to face questions about its commitment to PEPP.

(Reporting By Francesco Canepa; Editing by Catherine Evans) ((francesco.canepa@thomsonreuters.com; 004906975651247; Reuters Messaging: francesco.canepa.thomsonreuters.com@reuters.net))