Tanzanian officials on Friday dismissed allegations by an environmental activist group that Chinese diplomatic and military staff went on buying sprees for illegal ivory while on official visits to East Africa.

The country's foreign minister said the report by the UK-based Environmental Investigation Agency (EIA) was a "fabrication" designed to upset growing ties between Tanzania and China.

"We should ask ourselves as to why these allegations are surfacing a few days before (Tanzanian) President Jakaya Kikwete's visit to China," Foreign Minister Bernard Membe told parliament.

"These are mere fabrications. It is obvious that perpetrators of these allegations are people who do not wish to see our country attain development. The false reports were made out of jealousy seeing that Tanzania enjoys cordial relations with China," he said.

The minister asserted that the two countries have been sharing intelligence reports which have enabled numerous interceptions of ivory destined for China from Tanzania.

"China is doing a lot to help us solve this wildlife threatening crime," Tanzania's tourism minister, Lazaro Nyalandu, also told AFP.

"It is easy to see how cooked-up the report is, because saying that the Chinese president's plane was used to carry tusks is illogical. Such crafts are usually heavily guarded and surrounded by hundreds of people, leaving no room for any foul play," he added.

According to the EIA, when Chinese President Xi Jinping visited Tanzania in March 2013, members of his government and business delegation bought so much ivory that local prices doubled to $700 per kilo.

It quoted ivory traders as saying the buyers took advantage of a lack of security checks for diplomatic visitors to smuggle their purchases back to China on Xi's plane.

Similar sales were made on a previous trip by China's former president Hu Jintao, the report said, adding that Chinese embassy staff have been "major buyers", since at least 2006.

Chinese Foreign Ministry spokesman Hong Lei has also described the report as "groundless".

Tens of thousands of elephants are estimated to be slaughtered in Africa each year to feed rising Asian demand for ivory products, mostly from China, the continent's biggest trading partner.

Almost all ivory sales were banned in 1989 by the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES), to which both China and Tanzania are signatories.