Rwanda's ruling party has tightly controlled the political sphere for over two decades, but it is also accused of monopolising the economy via its very own conglomerate: Crystal Ventures.

The investment arm of the Rwandan Patriotic Front is the country's top private employer, with assets estimated at $500 million (426 million euros). It is present in almost every sector, from food processing to private security, building materials and real estate.

The company, formerly named Tristar, was born in 1995, a year after the then rebel RPF seized Kigali and put an end to a 100-day genocide which left 800,000 people, mostly from the Tutsi minority, dead.

With the country shattered and not a franc left in the treasury, the new authorities did not want to sit around and wait for a private sector to materialise and rebuild the nation.

"We wanted to see a difference made in our country where nobody was coming to invest," President Paul Kagame told a summit on investment in Africa in March.

The RPF delved into its war chest from the 1990-1994 civil war, built up with contributions from the Tutsi diaspora, to create the company and jump-start the private sector.

The precise ownership of the company is not clear. On its website it says it chooses investments to "make a significant impact on the socioeconomic landscape".

In 1998 Crystal Ventures partnered with South African telecoms giant MTN to put in place a mobile network in Rwanda. 

In 2015 the investment company sold its 20 percent stake in MTN Rwandacell, but observers remain concerned about the stranglehold Crystal Ventures has on the economy and whether this could scare away private investors.

A western diplomat, speaking on condition of anonymity, said the economy was "dominated by the party (RPF) and interests surrounding the party."

He referred to another conglomerate attached to the defence ministry: Horizon. One of its branches is the country's leading construction company, building roads and focusing on infrastructure development.

As Rwanda tries to draw in foreign investors "we are not sure that the private sector is as free and transparent as it should be," he told AFP, adding that in some sectors, such as dairy which is dominated by Crystal Ventures, there is no place for competition.

Kagame insists there is no favourable treatment in awarding tenders.

"I would challenge anybody to bring any fact ... there has been good competition," he said.