Abu Dhabi (AFP) - The four-day International Defence Exhibition and Conference (IDEX) kicked off Sunday in Abu Dhabi with the United Arab Emirates announcing 21 deals worth more than $1.2 billion.

IDEX spokesman Brigadier-General Rashid Mohammed Al Shamsi told reporters the Emirates struck deals with 15 local companies and six international firms to bolster its land and naval forces.

The UAE is a key partner in the Saudi-led coalition that intervened in Yemen in March 2015 after Shiite Huthi rebels stormed the capital Sanaa and advanced on second city Aden.

It is also seen as an important regional ally in the US-led coalition's fight against the jihadist Islamic State group in Iraq and Syria.

International contracts announced on Sunday included one with French firm Thales Underwater Systems SAS to buy sonars for the navy worth more than $23 million, and another with Britain's HESCO Group for defensive fortifications worth more than $24 million.

A statement also listed deals with Emirati companies, including one with International Golden Group for ammunition worth around $107 million.

The UAE also signed contracts with local firms to supply and instal electronic communications systems for the navy, armour mechanisms and monitoring equipment.

IDEX, which runs to Thursday, is one of the largest arms fairs in the Middle East and is held biannually to showcase the latest in defence technologies and innovations.