The Republican chairman of the Intelligence Committee in the U.S. House of Representatives says he has seen no evidence of inappropriate contacts between Russian officials and President Donald Trump's election campaign, prompting an outcry from Democrats in the lower legislative chamber.

Representative Devin Nunes of California on February 27 also dismissed Democratic calls for a special prosecutor to investigate the matter, and for the release of Trump's tax returns to clear up allegations he had business ties with Russia.

Nunes, who was a member of Trump's presidential transition team, said U.S. intelligence officials had not yet presented the committee with evidence of contacts between Trump campaign staff and Russian intelligence as some media have reported.

"It's been looked into and there's no evidence of anything there," Nunes said.

The committee's top Democrat, Representative Adam Schiff of California, said that it was too early to draw conclusions in a probe that's just starting, and questioned whether Nunes can objectively lead the investigation.

"When you begin an investigation, you don't begin by stating what you believe to be the conclusion," Schiff said.

House Democratic leader Nancy Pelosi said Nunes's remarks raised "serious questions about stonewalling" of the probe by Trump allies in Congress.

Based on reporting by AP, dpa, and Reuters