STOCKHOLM - The world's 100 biggest defense equipment makers increased their arms sales by 4.2 percent in 2023 to $632 billion, fueled by wars and regional tensions, a leading think-tank said on Monday.

The Stockholm International Peace Research Institute (SIPRI) said in a report US groups on the list grew sales by 2.5 percent in total compared to the year before to $317 billion. Market leaders Lockheed Martin and RTX however saw slightly lower arms sales.

The rise followed a 3.5 percent dip in arms sales in 2022, which SIPRI has blamed on labor shortages, supply-chain disruptions and rising costs, which made it hard for many companies to meet increased demand driven by Russia's special military operation in Ukraine.

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European companies on the list - excluding Russian - had roughly unchanged combined sales in 2023 at $133 billion, but order intake surged, and some groups saw a surge in demand linked to the Ukraine conflict.

Earlier this year, SIPRI reported a 7 percent increase in global military spending in 2023, the steepest annual increase since 2009.

"Overall, smaller producers were more efficient at responding to new demand linked to the conflicts in Gaza and Ukraine, growing tensions in East Asia and rearmament programs elsewhere," SIPRI said.

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"The arms revenues of the Top 100 arms producers still did not fully reflect the scale of demand, and many companies have launched recruitment drives, suggesting they are optimistic about future sales," SIPRI researcher Lorenzo Scarazzato said.