WASHINGTON (Reuters) - A former U.S. defense official who served on the Trump transition team said on Wednesday he had been prevented from speaking at a forum in China after its embassy in Washington failed to approve his visa.

Michael Pillsbury said he submitted a visa application on March 22 and it had not been granted in time for him to travel to Beijing for the April 14 event.

“So, is this a subtle message of some kind, or just a mistake,” Pillsbury told Reuters, adding he was still “waiting patiently for my visa to be issued”.

In Beijing, Foreign Ministry spokesman Lu Kang said he needed to look into the details of the situation, but in principle Chinese embassies handle visa applications in accordance with the law and China welcomed people-to-people exchanges with the United States.

“We welcome and are willing to proactively promote China-U.S. people-to-people exchanges and promote mutual understanding between the two countries,” he said.

Beijing and Washington are currently in talks to end a bitter trade war, but have also sparred over other issues such as human rights and U.S. support for self-ruled Taiwan, which China claims as its sacred territory.

Pillsbury said the visa delay could be in retaliation for U.S. visa restrictions on some Chinese academics, which the New York Times reported on Sunday, citing Chinese scholars who said their U.S. visas had been canceled.

Pillsbury said he had been invited to the forum by the Center for China and Globalization (CCG), which co-organized the event with an association under China’s Commerce Ministry.

A CCG invitation sent to journalists included Pillsbury on a list of confirmed attendees along with experts, ambassadors and former government officials from around the world.

The agenda said Pillsbury, a senior fellow focused on China at the conservative Hudson Institute, was to take part in a panel discussion on tensions in U.S.-China relations.

“I’m surprised at this delay which is usually reserved only for harsh critics of China,” said Pillsbury, whose book ‘The Hundred Year Marathon - China’s Secret Strategy to Replace America’ was translated by China’s National Defense University.

“Chinese have told me they consider my views to be a ‘moderate’ hawk not a ‘super hawk,’ who they would never invite,” he said.

A spokesman for the New York-based Asia Society said one of its experts, Wendy Cutler, a former U.S. trade official, had also not received a visa in time to attend the April forum.