Reuters reports that the size of the European Central Bank’s bond purchases will depend on the inflation outlook, the ECB’s chief economist Philip Lane said on Tuesday, warning once again about “highly uncertain” economic prospects for the euro zone.

“The overall envelope of PEPP (Pandemic Emergency Purchase Programme) purchases is a core determinant of the ECB’s overall monetary stance,” Lane said in a blog post.

“In line with the ECB’s price stability mandate, the inflation outlook plays the central role in determining the appropriate monetary stance.”