Amazon.com has agreed to buy Kiva Systems for $US775 million ($733 million) in cash, a deal that will bring more robotic technology to the e-commerce company's giant network of warehouses.

The acquisition, which has been approved by Kiva's stockholders, is expected to close in the second quarter of 2012, Amazon added in a statement.
Kiva develops robots that zip around warehouses, grabbing and moving shelves and crates full of products.
The technology helps retailers fulfill online orders quickly and with fewer workers.
Amazon has traditionally used more employees in its warehouses, or fulfillment centres as they are known.
However, Kiva's robots have been used by other e-commerce companies which have been acquired by Amazon in recent years, such as Quidsi and Zappos.
Fulfillment centres are crucial to Amazon's main online retail business. But the company also offers fulfillment services to other merchants, making the warehouses even more important.
"Amazon has long used automation in its fulfillment centres, and Kiva's technology is another way to improve productivity by bringing the products directly to employees to pick, pack and stow," said Dave Clark, vice president, global customer fulfillment, at Amazon.com.
(Reporting By Alistair Barr; Editing by Phil Berlowitz)