Questions have been raised about whether UK defense personnel have been involved in the internationally condemned Saudi Arabian-led military campaign in Yemen, following the release of UK documents detailing the number of British officers "embedded" with other nations' armed forces.

Following a Freedom of Information (FoI) request lodged by human rights activist group Reprieve, UK Defense Secretary Michael Fallon released figures showing how many British officers and HQ staff were embedded with the military forces of allies.

Today's UK Govt statement on "embedded personnel" doesn't tell us where they are or what they're doing: https://t.co/rFleojexgc — Reprieve (@Reprieve) December 17, 2015​

The figures revealed that as of November 30, 2015, there were 147 defense personnel embedded in the military headquarters of another nations, while an additional 30 embedded exchange officers were working with the armed forces of allies such as the US, France, Canada and Australia.

According to the list, Britain had the greatest involvement within US forces, with a total of 30 personnel embedded with American operations or headquarters.

The request was triggered after it was revealed earlier this year that British pilots had been taking part in bombing Daesh, also known as ISIL, targets while being "embedded" with US forces, despite the UK at the time not having been granted the parliamentary right to carry out the bombings.

What Are 'Coalition HQs'?

Despite the release of the figures, the nature of the information and the way it was released has been slammed by Reprieve, who have accused the government of a lack of transparency when it comes to detailing the specifics of where military are involved and what type of operations they are carrying out.

While listing the UK's involvement in the armed forces of some countries, the list also states that 94 British personnel are embedded with "coalition HQs", while others are listed as being involved in EU, NATO and UN HQs, sparking confusion about what coalitions and what countries this might refer to.

"The figures do not set out which operations the embedded personnel are involved in, or the locations where the embedded personnel are deployed. They also group a large number of embedded personnel under the heading 'coalition HQs' without making clear which coalitions those are — leaving open the possibility that these could be British personnel assisting the Saudi-led coalition in Yemen," Reprieve's statement read.

Information 'Almost Worthless'

Jennifer Gibson, staff attorney at Reprieve said the documents were a "long way from real transparency" and have triggered more questions than answers.

"It is impossible to tell what operations or even what countries these personnel are active in, making this information almost worthless," she said.

"The terms used are also hopelessly vague: what, for example, are the 'coalition HQs' where nearly 100 UK personnel are based? Is this the highly controversial Saudi-led coalition in Yemen, the long-standing coalition in Afghanistan, the coalition in Iraq and Syria, or another we don't know about?

"The UK Government is of course entitled to use military force, but if it is doing so then Parliament and the public deserve to know at the very least which wars we are sending our troops into and under whose command."

— Reprieve (@Reprieve) December 16, 2015 UK Def Sec Fallon not giving MPs much detail on #DroneStrikes and targeting individuals other than to say "I'm in charge". I thought PM was? — Jonathan Beale (@bealejonathan) December 16, 2015​

​On top of concerns that UK forces may be directly involved in legally contentious campaigns, like the Saudi-led bombing of Yemen, Reprieve criticized the fact that the figures are a snapshot of only one day, rather than a yearly cumulative, "meaning that they will not provide a complete picture of the activities of UK forces."

The group said it "has been seeking to map out the involvement of UK personnel in operations taking place without public knowledge and in countries where the UK is not at war," raising concerns that:

"…UK personnel, embedded with partner nations without proper safeguards, may potentially be in breach of both domestic and international law."