New Delhi, Nov. 12: No city in India is good enough to be rated as "clean".

The first ever survey on cities' cleanliness from the perspective of tourists, commissioned by the Union tourism ministry, has been unable to find any "filth-free" city.

Among the 36 cities rated - one each from every state and Union territory - Sikkim's capital Gangtok was found the "cleanest" while Chhattisgarh's capital Raipur was rated the "dirtiest".

Agra, where the Taj Mahal is a major tourist attraction, came at number 29 in the report prepared by a Delhi-based firm, Development & Research Services.

At number 7, Delhi trails cities like Panaji (second), Silvassa (third), Hyderabad (fourth), Ahmedabad (fifth) and Diu (sixth). Calcutta has been placed at the 13th position.

"We have been worried about negative feedback from the visitors on cleanliness, particularly foreigners, and wanted a professional survey on which city stands where," said an additional director-general in the tourism ministry. "Now, these findings will be used to promote cleanliness campaigns."

The report has analysed six factors to arrive at the ratings: cleanliness of sewers and drainage, effectiveness of garbage collection processes, cleanliness of public conveniences, drinking water facilities, eateries and ambience.

The data were collected by the survey team through interviews with tourists, residents and municipal officials. The marks were then allotted and colour codes awarded.

A score of over 80 earns the green category with the label "clean" while scores between 61 and 80 put cities in the blue bracket. These are followed by the black and red categories.

"None of the 36 cities could reach the highest category of green," said a survey team executive.

"Cities fared the worst in cleanliness of public conveniences. It was found to be poor across all cities."

As many as 17 cities are in the black category and the remaining 19 are tagged blue.

Rajeev Kohli, vice-president of the Indian Association of Tour Operators, said lack of cleanliness was a big put-off for foreign visitors.

"These studies would mean something if the government takes them seriously and launches initiatives to clean at least the most popular tourist destinations," he added.

"The ministry (tourism) has been spending so much on building the brand of Incredible India, why cannot it hire sweepers and cleaning instruments in cities and monuments where most tourists go?" asked Somesh Kartik of the Federation of Associations in Indian Tourism and Hospitality.

The tourism ministry spends over Rs 200 crore every year to publicise and market the Incredible India brand overseas.

In 2008, the Centre had fixed a target of getting 10 million foreign tourists by 2010. In 2014, the figure reached 7.70 million - still short of a target it was supposed to meet four years earlier.