The research questioned 100 HR directors on their attitudes towards language and communication skills and their approach to training. The questions were designed to cover the increasing number of professional non-native English speakers working in the UK as well as native English speakers.
More than three quarters (78%) of the HR directors questioned did not consider it necessary to train native English speakers to moderate their vocabulary when negotiating with non-native English speakers.
Nearly all of the respondents (98%) believed their non-native English speakers could communicate effectively in English.
Although 67% of those questioned believed that it was "very important" for business people to have a good cultural understanding of their trading partners; only 23% would offer training.
Only 4% believed the 'Basil Fawlty' approach of speaking more loudly would be effective in communicating with non-native English speakers.
Timothy Blake, chief executive of the London School of English, said: "The Brits may be reluctant to learn other languages, but this research suggests that we are not even prepared to invest in the training required to adapt our own language, accents and behaviour to help non-native English speakers understand us.
"A failure to communicate effectively with overseas business partners is a classic British mistake and it's disappointing to see that this is still not being addressed.
"In the current economic climate we need to ensure the UK remains a player in the world economy. If we aren't prepared to reach out and communicate with business people from all cultures, countries and backgrounds, we are in danger of dropping further and further down the global business league."
The report comes as news broke that the House of Lords committee had criticised laws that allow medics to practise anywhere across the EU. In a report it claims the wrong balance is being struck between allowing healthcare professionals to operate freely with the Union's borders and protecting the safety of patients, because they are not adequately trained in speaking English.
Hauke Tallon, director at London School of English, added:"In recent research we found that 98% of the HR directors we spoke to - who employed non-native English speakers in a professional capacity - believed that their employees could communicate effectively in English. We would question that.
"It's surprising that HR directors are so confident in the abilities of their native speakers, let alone non-native English speakers who, when working in specialist professions, often need training in the specific vocabulary, phrases and jargon used by these professions in the UK.
"The English language is full of complexities and nuance which can impact on understanding - particularly in professions which interact with the general public.
"The research also showed that 52% of HR directors did not consider that English spoken with a strong foreign accent would affect understanding. Yet 69% would not consider training to soften a strong accent. With the right training, it takes surprisingly little effort for someone with a competent grasp of English to soften their accent. This could make the difference between clarity and confusion."
