Statutory sick pay and government assistance for jobless and self-employed people in the UK have been found to breach international legal obligations.

The amount of money available to those claiming statutory sick pay and employment support allowance is “manifestly inadequate”, according to the guardians of an international charter ratified by the UK in 1962.

It has been further ruled that a change in the law three years ago to lower the level of health and safety regulation that applies to the self-employed has created a discriminatory system that does not conform to the European social charter – a legally binding counterpart to the European convention on human rights.

The rulings were made on Wednesday by the European committee of social rights, a monitoring body of the 47-nation Council of Europe, an international organisation formed in the wake of the second world war to protect human rights, democracy and the rule of law.

The committee found that sick and unemployed people were, in many cases, receiving less than 40% of the median income in the UK, which it said was £152.22 a week, although some were in receipt of top-up payments.

“Regardless of the additional social assistance benefits which might be available, the committee considers that the level of these benefits is manifestly inadequate,” the committee said.

Three years ago the government, as part of an attempt to slash “red tape”, took certain types of self-employed work out of the 1974 Health and Safety at Work Act.

The committee, while recognising that only those in relatively less risky work were not now covered by health and safety regulations, reported that the UK was again not living up to its commitments in the charter.

“All workers, including the self-employed, must be covered by health and safety at work regulations as long as employed and self-employed workers are normally exposed to the same risks,” the committee said.

The analysis of the social security system in the UK was one of 33 studies of signatories to the charter made by the committee, based in Strasbourg, and covered the period from 1 January 2012 to 31 December 2015.

When previously challenged by the committee, the UK government has taken a tough line in response. Three years ago, Iain Duncan Smith, the then welfare secretary, described findings criticising the level of ESA payments as “lunacy”, adding that the UK paid out £204bn in benefits and pensions a year.

A DWP spokesperson said: “Our welfare system is among the best in the world and we are committed to helping people improve their lives. We spend over £90bn a year supporting people of working age, including those who are out of work or on a low income.”