Heavy machinery maker Caterpillar Inc said on Thursday that its retail sales of machines had declined at a faster pace in May, sending its shares lower.

World sales, including Cat Japan, fell 43 percent in the three months ended in May from a year earlier, compared with a 39 percent decline in the three months ended in April, Caterpillar said in a regulatory filing on Thursday.

Three-month retail sales in North America were down 57 percent, compared with declines of 51 percent and 41 percent in April and March, respectively. Retail sales for the rest of the world fell 35 percent over the three-month period, also at a faster pace than in the prior two months.

The pace of sales declines also worsened in Latin America, but improved slightly in Caterpillar's Europe, Africa and Middle East region.

Caterpillar shares were down 56 cents, or 1.6 percent, at $34.24 on the New York Stock Exchange. (Reporting by Nick Zieminski; Editing by Lisa Von Ahn)