ABUJA, Nov 18 (Reuters) - U.S. Secretary of State Antony Blinken said on Thursday that Washington"s involvement in infrastructure in Africa was not about China, but intended to improve the standard of infrastructure without countries becoming burdened by debt. On a visit to Africa"s most populous country, Blinken was asked about U.S.-China competition over infrastructure investment on the continent, where China has grown its influence in recent years through such investments. "When it comes to infrastructure investment, again, this is not about China or anyone else, it is about what we would like to think of as a race to the top when it comes to those investments," Blinken said at a joint news conference with Nigerian Foreign Affairs Minister Geoffrey Onyeama. Blinken said investment from China in Africa was in principle a good thing, but that countries should not be left with "tremendous debt that they cannot repay", adding that workers rights, environmental protections and safeguards against corruption should also be in place. Developed countries in the G7 would invest in Africa as part of the so-called Build Back Better World programme, he added. Blinken signed a $2.17 billion development assistance program with Onyeama on Thursday and said Washington would also continue to invest in security in Nigeria. Onyeama said Nigeria needed investment from China to tackle a severe infrastructure deficit, and said the debt it has taken on was "sustainable". China is one of the major bilateral lenders to Nigeria and has provided financing for infrastructure development such as roads, rail and gas pipelines. Nigeria"s public debt office says on its website that Chinese debt stood at $3.121 billion or 3.94% of the country"s total public debt stock as of March 2020. "We saw a great opportunity with the Chinese," Onyeama said. "They are used to a lot of these huge capital projects and infrastructure projects."