FRANKFURT, Sept 27 (Reuters) - European drugmakers warned that a proposed complete ban on substances known as PFAS or "forever chemicals" would render medicine production in the region impossible, part of a high-stakes wrangle between manufacturers and environmental regulators.

The European Union started to consider in February a ban of the widely used but potentially harmful substances, in what could become the bloc's most extensive piece of regulation of the chemical industry.

A six-month consultation period to give impacted companies and industries an opportunity to put their views forward ended on Monday, with the European Chemicals Agency (ECHA) registering 5,600 comments.

"The entire pharmaceutical industry would no longer be able to manufacture active pharmaceutical ingredients ... or associated medicinal products in the EEA," if no exemptions, or derogations, are included in the draft, the European Federation of Pharmaceutical Industries and Associations (EFPIA) said in a statement.

The EEA, or European Economic Area, includes 27 EU member states plus Liechtenstein, Iceland and Norway.

"A total ban would see medicines’ manufacturing in the EU grind to a halt in under three years," said EFPIA's director general, Nathalie Moll.

The group, which counts pharmaceutical majors with European operations including Pfizer, Roche and Novartis as members, said that PFAS are used in drug production, and some PFAS with no or low identified risks go directly into medicines.

It does not oppose regulating certain harmful PFAS, the group added.

Among critical responses from other industries, the European chemical makers' association Cefic has called for "balanced" regulation of PFAS, saying a ban would hobble the production of batteries, semi-conductors, electric vehicles and renewable energy production, among other products.

EFPIA said it had provided "scientific and technical evidence to justify derogations and prevent medicine shortages" under ECHA's consultation.

The moniker "forever chemicals" stems from their ability to accumulate in water and soils because they do not decompose as a result of an extremely strong bond between carbon and fluorine atoms.

The chemicals are in use in tens of thousands of products and machines, including cars, textiles, medical gear, windmills and non-stick pans due to their long-term resistance to extreme temperatures and corrosion.

But PFAS have also been linked to health risks like cancer, hormonal dysfunction and a weakened immune system as well as environmental damage.

According to the planned EU regulation, companies would be given a transition period of 18 months and, in addition, up to 12 years to find alternative substances, depending on the industry or product use.

(Reporting by Ludwig Burger;Editing by Elaine Hardcastle)