By Tristana Moore BBC News, Berlin

Ramona Wonneberger's Be happy website spreads the message

"Germany is a country of complainers," says Thomas Kuwatsch.

"Some people complain about everything, the weather, the train is late, the coffee is bad or they whinge about high fuel prices. If you go to India, they're happy if their train arrives at all. We complain about stupid things in Europe."

Mr Kuwatsch works for an IT company called "Nutzwerk", which is based in Leipzig.

It is a small firm, which employs 16 people. But there is something that distinguishes Nutzwerk from other companies.

Employees can be fired if they are caught complaining in the office.

It may sound absurd, but employees have a clause in their contracts which states: "moaning and whinging at Nutzwerk is forbidden... except when accompanied with a constructive suggestion as to how to improve the situation".

Negative energy

Ramona Wonneberger, chief executive of Nutzwerk, came up with the idea.

She claims that "negative energy" puts a dampener not just on workers' moods, but also on productivity.

If people are sad or bad-tempered, they don't concentrate on their work Thomas Kuwatsch Nutzwerk employee

"If you want to have fun in your company, and you want to reach a big target you have no chance if your employees are always angry," she says, smiling broadly. "They waste time, and they waste the company's time."

Ramona Wonneberger has set up her own website, called Be happy, to spread her message across the country.

When I arrive at the company in Leipzig, it is a cold, grey winter's day.

As soon as I open the main door, two ebullient receptionists greet me. "Please can we take your coats?" they ask, with smiles beaming across their faces.

It soon dawned on me that everyone in the office abided by the policy.

At lunchtime, the workers sit together, exchanging amusing stories and cracking jokes.

The firm says turnover has doubled since whingeing was banned

"I'm so pleased that whingeing is not allowed," says Cathleen Sochor, who has been with the firm for several years.

"My friends tell me it's strange, they call it a 'miracle' company. And when I meet my friends, and they start complaining about something, I'm always silent in the corner, as I have nothing to be grumpy about.

"I don't feel I'm being watched, or observed in the office. I am always like this, I laugh and I like laughing. It's good for your character, happiness is very important."

Nearby, one wall was covered with photos full of happy faces - the pictures had been taken on a work trip to Majorca.

The ban on whingeing is taken seriously. So far, three employees have been dismissed. Two workers had been given repeated warnings, and one woman chose to go voluntarily.

Contagious atmosphere

But doesn't all this smack of a "Big Brother" state?

"Look, we don't have any cameras or microphones in the office," says Mr Kuwatsch.

"You control yourself, you control your moods. We say to everyone who works here: if you're not in a good mood, then just stay at home. If people are sad or bad-tempered, they don't concentrate on their work. I think that all the people who work here are happier, both in the workplace and in their private lives."

To people who have just joined Nutzwerk, the friendly atmosphere is contagious.

"I'm so happy when I come to work," says Damola Babalola, who is from Nigeria and has been working in the company for the last five months.

"My colleagues are like my family. Everyone is so friendly and relaxed. We never have cause to complain, and even if we did, we'd make a constructive suggestion."

According to Mrs Wonneberger, the company's turnover has doubled since the anti-whingeing policy was introduced.

"I hope that when you leave our company now, you have a good feeling," says Ramona Wonneberger, as I was saying goodbye.

I look outside. It is still snowing and the sun is obscured by a blanket of grey clouds. I don't dare grumble about the weather.

Instead, I smile and as I leave the building, I feel a sense of relief.

Is it right to ban whingers? Could this have a positive impact on productivity? Would this work in your office?