citroen berlingo 1.9 diesel van 2001, oil pump drive chain slack?

I removed the sump on my 1.9 non turbo diesel van as was leaking, noticed drive chain from crankshaft to oil pump drive sprocket was very slack, is it possible to adjust this chain, or remove a link? if this is not possible, could i remove oil pump and add washers between pump and block or will i need a new drive chain?

Mark
May 2008