BRUSSELS (Reuters) -The EU's Ombudsman on Tuesday demanded the European Commission explain why it fast-tracked proposals to curb sustainability laws, in response to a complaint by campaigners accusing Brussels of weakening the rules without consulting the public.

In February, the Commission proposed legal changes that would exempt thousands of smaller European businesses from European Union sustainability reporting rules - a move designed to simplify regulation for industries struggling to compete with rivals in China and the U.S., where President Donald Trump is rolling back regulation.

The EU's Ombudsman has demanded the Commission explain why it did not conduct a full analysis of the impact of these proposals, consult the public on the changes, or assess whether the proposals were in line with Europe's climate change commitments.

When proposing new EU laws, the Commission usually conducts an impact assessment to examine their effect.

It can skip this when a law is an urgent response to a crisis and did not carry out an assessment in the proposals to simplify the green reporting rules.

"Based on the material made available to date, the Commission does not seem to have adequately justified derogating from its rules in this case," Ombudsman Teresa Anjinho said in a letter to the Commission, published on Tuesday.

"The Commission did not indicate any sudden or unexpected event that would justify the urgency," she said.

Anjinho also noted that the Commission had given its internal departments just 24 hours to assess the plans, starting on a Friday evening, rather than the standard 10-day internal consultation.

A Commission spokesperson said it would respond to the questions, and that swift changes had been needed since the reporting requirements applied to some companies already this year.

"Businesses and member states urgently needed legal certainty to comply with the sustainability framework," the spokesperson told a regular press briefing.

The European Ombudsman investigates cases of maladministration in EU institutions. The Commission has until September 15 to respond to the questions.