A new study has concluded that several of the most high-profile trade deals signed by the UK government post-Brexit will be worth less to the country's economy than initially thought.

Analysis by the non-partisan Office for Budget Responsibility (OBR) noted that in particular, the UK's accession to the Comprehensive and Progressive Agreement for Trans-Pacific Partnership (CPTPP) will not bring the benefits the government had claimed.

Upon joining the pact earlier this year, business secretary Kemi Badenoch had stated the arrangement with 11 Asia-Pacific nations would add 0.08 percent to the country's GDP - a figure which critics had already slammed as underwhelming. However, the OBR's analysis suggested that the true number will be just half that, at 0.04 percent over 15 years.

Elsewhere, the body also concluded that two separate bilateral deals with Australia and New Zealand had the potential to increase the level of real GDP by a combined 0.1 percent by 2035 - much less than the estimate of one percent provided by the government.

Commenting on the figures, trade expert David Henig told the Observer that the impact of the UK joining CPTPP had been "overhyped" and that, while some companies do stand to benefit from increased access to Asia-Pacific markets, the overall impact will be "very small".

If the UK wants to grow its economy, it should instead focus on expanding trade with the EU, he added. The OBR also noted the UK's GDP will be four percent lower than if it had remained in the EU single market - the equivalent of about £100 billion.

However, the government maintains that the UK will benefit from membership in pacts such as CPTPP. New foreign secretary David Cameron described the agreement as a "vital step" in the country's post-Brexit development in his maiden speech to the House of Lords, adding it will put the UK “at the heart of a group of some of the world’s most dynamic economies".