Washington (CNN) -- Venezuelan officials have notified the United States about the arrest of an American citizen, a U.S. State Department spokeswoman said Tuesday.
Venezuelan President Hugo Chavez has accused the detainee of having "all the appearances of a mercenary."
The man has not been identified.
"The Venezuelans did confirm to us here in Washington yesterday ... that they do have an American citizen under custody," State Department spokeswoman Victoria Nuland told reporters.
"They did not follow usual channels and notify our embassy in capital, nor have they responded to our request for consular access to him," she said.
Chavez said on Tuesday that access to the detainee would not be a problem.
"Foreign Minister Maduro has informed me of the U.S. government's request through its embassy to have access to the detainee. Of course, we approve it, they request it today and tomorrow they will have contact with the detainee," Chávez said on Venezuela's state-run VTV.
Chavez, who is running for re-election, first announced the arrest last week. The man was detained while trying to cross the border from Colombia into Venezuela, the president said.
Late Tuesday, Chavez reported that authorities were continuing to investigate the matter and had reached out to the Colombian government.
The detainee told authorities he was a former Marine, but otherwise refused to provide information, according to Chavez, who has described the man's behavior as "suspicious."
Chavez said the passport the man was carrying had stamps from recent years in Iraq, Afghanistan and Libya. The president also said police seized a notebook with written coordinates.
"It sends a powerful signal, how this citizen wanted to illegally enter the country, to do who knows what. ... He says he was fleeing from I don't know who. The certainty is that this forces us to activate many more alarms everywhere," Chavez said last week.
The Venezuelan president has repeatedly accused U.S. officials and members of Venezuela's opposition of plotting to destabilize the country's government.
CNN's Paula Daza contributed to this report.