DIAMNIADIO, Senegal -- China's president pledged to offer Africa one billion COVID vaccine doses on Monday, with the continent struggling to acquire enough jabs to immunise against the disease.

In a speech made via videolink to a China-Africa summit near Senegal's capital Dakar, President Xi Jinping said his country would donate 600 million doses directly.

A further 400 million doses would come from other sources, such as investments in production sites, which are sorely lacking across much of Africa.

Xi's promise comes as part of a forum between China and African states with an emphasis on trade and security, among other issues, held in the city of Diamniadio near Senegal's seaside capital.

China invests heavily in Africa, and is the continent's largest trading partner with direct trade worth over $200 billion in 2019, according to the Chinese embassy in Dakar.

Beijing has also donated millions of doses of its home-produced Sinopharm vaccine to poor African countries since the start of the pandemic.

Critics charge that China's largesse forms part of a diplomatic offensive, however.

"We must continue to fight together against Covid," Xi told the summit, adding that China would send about 1,500 medical workers to Africa.

"We must prioritise the protection of our people and close the vaccination gap," he also said.

Vaccination rates in Africa are low compared to the rest of the world, with many states at the mercy of foreign donations due to the lack of local production facilities and prohibitive costs of mass purchases.

The summit in Senegal follows a visit this month from US Secretary of State Antony Blinken to Kenya, Nigeria and Senegal, against a backdrop of growing rivalry between Beijing and Washington.

Blinken discussed boosting local vaccine-production sites with leaders during the visit, and alluded to the sometimes fraught nature of the continent's deep relationship with China.

Last month, US President Joe Biden also announced vaccine donations to Africa, pledging 17 million doses of the single-shot Johnson & Johnson vaccine to the African Union.

- Debt wariness -

At the forum, Senegalese economy minister Amadou Hott told attendees that a shift in the commercial relationship with China was needed -- away from projects financed by African governments taking on large debts.

"We need more equity investment," he said, pushing for Chinese entrepreneurs to invest in local companies.

"This pandemic has shown the need for our economies to produce more and become sovereign in strategic sectors," he added, pointing to the pharmaceutical and agriculture sectors, among others.

Beijing has often faced accusations of "debt-trap diplomacy" due to the scale of its lending to developing countries in Africa and elsewhere, using its creditor status to extract diplomatic and commercial concessions.

Blinken, in his recent trip to Africa, referenced the accusations without naming China explicitly, saying in an address in Nigeria that Africans have been "wary of the strings" that often come with foreign engagement.

But China rejects the charges.

Wu Peng, the head of the Africa department at China's foreign ministry, told a news conference in Beijing on Friday that "debt-trap" accusations amount to a cliche.

China takes debt sustainability seriously, state-run news agency Xinhua quoted him as saying.

Peng added that a general lack of funding is holding back African development, rather than unmanageable debts.