It is the mother tongue of Goethe, Schiller and Brecht, a language still spoken by more than 100 million people worldwide. But an increasing number of linguists now fear German is under mortal danger from a torrent of anglicisms flooding into the nation's vocabulary.

The German Language Association (Verein Deutsche Sprache, or VDS) fears that German could become a "peripheral" language if steps are not taken to protect it from foreign invasions.

Each month the VDS updates its Anglicism Index, which reports new English words which have crept into common parlance and then suggests home grown alternatives. The latest entries include "follower", "live-stream" and "socializing" which ought really, it says, be "Anhänger", "Direkt-Datenstrom" and "Geselligkeit". Other unwelcome new additions are classic examples of the mongrel known as "Denglisch" – "business breakfast" and "eye catcher", neither of which are used by native English speakers.

"German has been losing its importance for 100 years," said Holger Klatte, spokesman of the VDS. "Particularly in the areas of technology, medicine, the internet and the economy, English is becoming ever more important. There are not enough new German words being invented, and many people are shut out of the conversation because they can't understand it."

He warned: "The German language is not only losing its influence but will also at some point become a peripheral language."

Germany is classed as one of the world's major languages, and is the most widely spoken first language in Europe. The VDS has more than 33,000 paying members and is growing.

There are certain situations nowadays where it is "nigh on impossible" to speak German in Germany, said Klatte – "for example if you work in marketing, there just isn't the vocabulary". The German word for marketing, incidentally, is das Marketing.

Klatte's own pet hate, he said, was seeing shops displaying signs promising "further reductions" – "there is no need at all for them to use the English in that situation".

The VDS would like to see Germany follow France's example and do more to protect and nurture the language. German public radio should be obliged to play a higher percentage of German-language music, said Klatte, and the government should introduce a law forcing manufacturers to include German information on product labels.

"We have a special responsibility to protect our language because it is a language of particular cultural importance," he said. "Our language is our expression of our culture and we have a duty to nurture it and ensure its future development."

Not everyone in Germany sees English as a threat. In the south-western spa town of Wiesbaden, the VDS's rival, the Society for the German Language (Gesellschaft für deutsche Sprache) is of the firm belief that German is not at risk of marginalisation, even less, extinction.

"Contrary to common belief, only 1%-3% of the average German's vocabulary of 5,000 words is made up of anglicisms," said Andrea-Eva Ewels, the society's managing director. "We don't see English as the enemy. We're of the opinion that English can enrich our language, just as many other languages, for example French and Latin, have influenced German over history."

But she admitted that many Germans were unhappy with the anglicisation of their mother tongue. "We did a survey in 2008 and 39% of respondents said they did not like anglicisms," she said. Interestingly, Germans in the east were more unhappy with the anglicisation of their language - 46% objected compared with 37% in the west.

Despite the onslaught of English, some attempts are being made to stem the tide. In January, Siemens announced it would use fewer anglicisms in future. The VDS has noisily criticised the company for years, complaining last year that there was no need for them to refer to "renewable energy" when "erneuerbare Energie" would do just as well, ditto "Smart Grids" (intelligente Stromnetze) and "Healthcare" (Medizintechnik).

Last year Germany's transport minister, Peter Ramsauer, banned his staff from using a string of anglicisms, including "Laptops", "Tickets" and "Flip-charts".