ROME (Reuters) -Raytheon and Lockheed Martin ( LMT ) will be the major customers of Avio's planned solid rocket motor plant in the United States, the Italian rocket maker said on Monday.

Raytheon, which is the defence arm of aerospace giant RTX, and Lockheed Martin ( LMT ) will have preferred access to a share of production at the plant, Avio said in separate statements on the two agreements.

Avio has not announced where the plant will be built but has said it will be operational by early 2028.

"This agreement will help establish an additional supplier of solid rocket motors within the U.S.," said Bob Butz, Vice President of Operations, Supply Chain and Quality at Raytheon.

Avio will direct 80% of an ongoing 400 million euro ($466.48 million) capital increase for development of the site, its CEO told Reuters in October.

"The establishment of Avio's SRM facility will allow us to bring our proven solid propulsion expertise to the United States, contributing to the innovation and development of a critical industrial supply chain," Jim Syring, CEO of Avio USA, said.

The solid rocket motor (SRM) market is growing due to rising military spending globally, particularly for missiles and tactical weapon systems, as countries aim to upgrade their defence capabilities with advanced missile technologies.

The President of Lockheed Martin Missiles and Fire Control Tim Cahill said the collaboration with Avio would allow the group to commit to a "diverse, resilient supply chain for solid rocket motors".

Avio CEO Giulio Ranzo told Reuters that the two deals were "fundamental, and give great solidity" to Avio's U.S. plan.

They come right after Italian state-controlled defence group Leonardo cut its share in Avio to a little more than 19% and said last week that it was not interested in investing further in the group because it is already part of European missile maker MBDA.

($1 = 0.8575 euros)