Bosses at last year's Shoreham Air Show were not aware of the manoeuvres planned as part of the display which ended in tragedy - some of which were banned under its flying permit, it has been revealed.

Eleven people were killed when a Hawker Hunter plane crashed onto the busy A27 in West Sussex on August 22.

Lawyers representing the families of victims welcomed the report, but said it was "disappointing" it had taken a disaster of Shoreham's scale for changes to be made.

An official report by the Air Accidents Investigation Branch (AAIB) found a "number of deficiencies" in the event's risk assessment - some of which may have been avoided had the event's flight display director (FDD) known what was planned by pilot Andy Hill, who survived the crash.

It added that it was "not clear" that those who carried out the assessment had "a full understanding" of its purpose in controlling potential risks to the public.

A permit had been issued for the event, stating the aircraft "shall not be flown over any assembly of persons, or any congested area of a city, town or settlement".

However, the investigation found the air show had previously violated this condition, flying over roads and the nearby town of Lancing during displays performed in the 2014 Air Show.

"Evidence from the 2014 Shoreham display indicated that it was not possible for G-BXFI to complete the intended sequence of manoeuvres while complying with the condition of its Permit to Fly; not to overfly congested areas," the report stated.

"Knowledge of its intended routine would have enabled the FDD to determine if its attendance at the flying display was appropriate."

The official report comes after ITV News revealed in February that Mr Hill had been involved in a previous incident in 2014, when a stop call was issued because his jet had been flying too low above the crowd.

After the event, the FDD then submitted risk assessments for two further displays to the Civil Aviation Authority which "were not materially different from that for Shoreham."

A total of 14 safety recommendations were made, including:

Read: AAIB makes 14 air show display recommendations

Solicitors firm Irwin Mitchell will be representing victims and their families at the pre-inquest review into their deaths on March 22.

The 11 victims of the crash were:

Read: Tributes to the victims of the Shoreham air disaster

Clive Garner, who leads the company's aviation team, said:

A Civil Aviation Authority spokesman said they had already taken action on a number of areas covered by the recommendations, and would "consider" the report in full.

"We will also factor the AAIB's findings into our ongoing review of air display safety, which we expect to complete in the coming weeks," they added.