WASHINGTON - A U.S. diplomat urged Pakistan on Wednesday to investigate reported irregularities with last month's general election and re-run the vote in affected constituencies if it found credible evidence of interference.

"The Election Commission of Pakistan, should it find that these irregularities are substantiated, should re-run elections (in constituencies) where there has been interference," Donald Lu, the State Department's top official for South and Central Asia, told a congressional panel.

Pakistan's election was marred by arrests and violence ahead of the early-February vote, an internet shutdown on election day and unusually delayed results leading to accusations that the vote was rigged. Shehbaz Sharif became prime minister on March 4, heading a coalition after his party won fewer seats than candidates backed by jailed former Prime Minister Imran Khan.

"We have never used the term 'free and fair' in the characterization of this election," Lu testified to a subcommittee of the House of Representatives Foreign Affairs Committee examining Pakistan's democracy and its relations with the U.S.

"We have expressed serious concerns about the pre-election environment: violence that occurred - terrorism and political violence," he said. "We have expressed concern about the failure to register individual candidates and political parties, the mass arrests of those in opposition, the shutdown of internet, and censorship and pressure placed on journalists."

Britain and the European Union have also expressed concern about reported irregularities and urged a probe. United Nations Secretary-General Antonio Guterres expressed concern about violence and the suspension of mobile communications services.

Responding to questions, Lu denied allegations by Khan that he had interfered in Khan's 2022 removal from power

"These allegations, this conspiracy theory, is a lie. It is a complete falsehood," Lu said, as some members of the audience shouted protests at his denial. Lu said he had faced threats over the allegations.

Khan was ousted after falling out with Pakistan's powerful military, which denies meddling in politics. He alleged the U.S. and Pakistan's military played a role in his ouster through a parliamentary no-confidence vote.

Multiple legal cases were brought against Khan after he was ousted, which disqualified him as a candidate in February's election and sentenced him to long prison terms. He denies wrongdoing and remains in jail. REUTERS