Just five per cent of Britain's top firms have issued net-zero plans that would be "credible" under government guidelines, according to a study published on Monday.
Consultancy EY revealed the key finding after examining net-zero ambitions of companies listed on London's benchmark FTSE 100 index.
Britain is targeting carbon neutrality by 2050 and wants businesses to outline how they will achieve this.
"While over 80 per cent of UK listed firms say they are committed to becoming net zero by 2050, the majority -- 95 per cent -- have not yet publicly disclosed detailed, actionable transition plans," EY said in the study.
Only five per cent have plans "that would be deemed 'credible' or sufficiently detailed under draft government guidance", it added.
Britain hosted the COP26 UN climate summit in late 2021, when it vowed to ensure listed companies detail their plans, although no deadline was given.
The Transition Plan Taskforce (TPT) framework aims to provide guidance to bring plans in line with the UK's net-zero target.
However, the government has not yet made the TPT mandatory and its new green strategy last week delayed a second consultation on the framework until later in the year.
"Business will need to transition if the UK is to reach net zero, and mandatory disclosure is a vital step in this journey," EY added on Monday.
"But we're seeing hesitation on the part of business and government, despite the need for urgency."
The study comes after London announced a multi-billion-pound green plan last week.
The government updated its energy security plan to ramp up renewable and nuclear power.
However, the proposals were slammed by political opponents and environmentalists who accused it of not going far enough -- and placing at risk the 2050 target.
The CBI business lobby warned in January that Britain was lagging behind on the green investment growth, particularly with the United States and the European Union.
