Nestlé attempts to buy pet care company Ralston Purina has been hit by anti-trust concerns.

The US Federal Trade Commission (FTC) has sought more information on the US$10bn deal after a rival pet food maker voiced concerns to the FTC about the size and power of a combined Nestlé and Ralston Purina company. The Nestlé-Purina combination would control nearly 70% of the dry cat food market.

The FTC approached both companies with a 'second request' for information on Friday, a move that extends the deadline for approving the transaction.

The FTC has another 30 days to decide whether to oppose the merger once Nestlé and Ralston have submitted all the required information. Both parties still expect to close the deal before the 31 December deadline.