The economic pledge signed on Tuesday will help the Czech Republic become China's "entry gate" into the European Union, said Czech Republic President Milos Zeman, as the two leaders inked the landmark deal.

President Xi, who is in Prague on a first visit by a Chinese leader to the country, said the partnership "sets a political direction for the development of our relations in the future."

Xi was greeted with a rare 21 salvos of artillery at the Prague Castle, the seat of the presidency, for the signing.

The Chinese leader also backed a series of other deals on cooperation in health, transport, IT, science, tourism, banking and other fields as well a partnership deal between the countries' capitals.

China's CEFC, among the country's top 10 private companies, recently acquired stakes in a Czech airline, a brewery, two media groups and a top football team.

Protests go ahead

But despite a pledge that Zeman said would be worth 3.5 billion euros ($3.93 billion) in 2016 alone, the announcement failed to silence China's critics.

Several dozen members of China's banned Falun Gong religious movement demonstrated outside Prague Castle during the meeting.

Later in the day, around 500 protesters rallied in central Prague, waving Tibetan flags and chanting "Freedom for Tibet" along with anti-Zeman slogans.

Riot police separated the protesters from dozens of Chinese supporters with giant Chinese flags before they marched through the city for another protest rally near the Prague Castle.

In the evening, a mass for the victims of the Chinese communist regime was scheduled in a Catholic church in Prague.

On Monday, police arrested 12 people after pro-Tibetan demonstrators scuffled with crowds who had turned out to welcome the Chinese leader.

Chinese flags were defaced, and a huge billboard of Tibetan spiritual leader, the Dalai Lama, meeting with the late Czech President Vaclav Havel was erected on the road leading from the airport to the city.

China, which has ruled Tibet since 1951, accuses the Dalai Lama of supporting separatism and violence in the region.

A 71-year-old pro-Russian ex-communist, Zeman was the only European head of state to attend a military parade in Beijing last September commemorating Japan's surrender at the end of World War II.