WASHINGTON, June 9 (Reuters) - U.S. wholesale inventories increased strongly in April as businesses continued to replenish stocks to meet pent-up demand, supporting expectations for robust economic growth this quarter. The Commerce Department said on Wednesday that wholesale inventories rose 0.8% as estimated last month. Stocks at wholesalers advanced 1.2% in March. Wholesale inventories increased 5.2% in April from a year earlier. Inventories are a key part of gross domestic product. Economists polled by Reuters had forecast that April’s increase in wholesale inventories would be unrevised. The component of wholesale inventories that goes into the calculation of gross domestic product also increased 0.8%. Businesses ran down inventories in the first quarter amid a burst in domestic demand. The inventory drawdown subtracted nearly three percentage points from GDP growth last quarter. Still, the economy grew at a robust 6.4% annualized rate in the January-March period after expanding at a 4.3% pace in the fourth quarter. Most economists are forecasting double-digit GDP growth in the second quarter. Sales at wholesalers rose 0.8% after accelerating 4.3% in March. At April’s sales pace it would take wholesalers 1.22 months to clear shelves, unchanged from March. That is the shortest period since September 2014. (Reporting by Lucia Mutikani; Editing by Andrea Ricci) Our Standards: The Thomson Reuters Trust Principles.