Opponents of the Obama administration's efforts to renew ties with Cuba are criticizing U.S. officials for downplaying human rights concerns in advance of the openings of embassies in the two countries as the Castro regime cracks down on activists.

Several Cuban diplomats are in town Monday to mark the openings of their embassy in Washington and to meet with Secretary of State John Kerry and other U.S. officials, including a trip to Capitol Hill.

The U.S. hoisted a Cuban flag in the State Department lobby Monday morning to mark the renewing of diplomatic ties with Havana.

But vocal opponents of re-establishing relations with Cuba argue that the Castro regime is showing no signs of reducing the number of human rights activists they arrest in the days leading up to the embassy openings.

"On the eve of the U.S. error in opening an embassy in #Cuba, #bertasolerf reports more arrests by state security," Rep. Ileana Ros-Lehtinen, R-Fla., tweeted over the weekend.

Berta Solerf is a leader of the Ladies in White, an opposition movement in Cuba founded in 2003 by wives and other relatives of jailed dissidents.

Ros-Lehtinen, with Florida GOP Reps. Mario Diaz-Balart and Carlos Curbelo, plan to hold a press conference in Miami later Monday to protest the embassy openings.

Over the weekend, she told a local CBS Florida affiliate that opening the embassy is a danger to the U.S. because "Cuba has a very sophisticated espionage network operating in the United States, and we're giving them license to operate the espionage activities."

"[The Cuban government] has not changed their feelings about the United States being the enemy — no matter what deals they sign, she said. "I think it's dangerous. I think it puts us at risk — it doesn't make us any safer.

"I don't think having five staffers in an embassy or having an interest section and calling it an embassy will help the United States or help the Cuban people – it's just another legacy-shopping [moment] for President Obama," she added.

The Obama administration has hailed the embassy openings as a historic moment that will allow for more U.S. diplomatic contact with the Cuban people.

State Department spokesman John Kirby said Friday that U.S. officials would have enough access to "do the work they need to do in Cuba."

"It is not a restriction-free environment, as I think you can understand, but we're comfortable with that – through the negotiations that we had with Cuban authorities that they will be able to do the job that they need to do," he said.

The Cuban delegation is scheduled to meet with Kerry at 1 p.m. Thursday, in what Kirby said would be a "substantive discussion" that will include the Cuban people's access to telecommunications, coordination on health issues, human rights, migration and "fugitives in law enforcement."

In a conference call with reporters later Friday, a senior administration official declined to provide more detail on the topics Kerry and top Cuban officials will discuss and whether the U.S. will demand the release of more Cuban political prisoners or respond to Havana's demand for the return of Guantanamo Bay.

"Yeah, I'm not going to try to talk about the — I don't really want to talk about the conversation that the two ministers will have," the official said. "… And so on human rights, we won't get into specifics, but we've had a dialogue with them already and we've had a pretty robust conversation with them, and we expect that to be continued through the discussion by the ministers."

Latin American-focused newspapers, citing democracy activists in Cuba, reported late last week that Cuban police have escalated a crackdown on dissidents in the days leading up to the embassy openings.

On July 12, the PanAmPost, an Florida-based American news and analysis website, reported that Cuban authorities detained at least 120 dissidents, including 40 members of the Ladies in White House and Solerf.

The same day Cuban authorities arrested Solerf, it also detained well-known activist Jorge "Antunez" Garcia, who was House Speaker John Boehner's controversial guest for the State of the Union address, as well as artist Tania Bruguera, among others, the website reported.

Sources in the Washington Cuban-American community lost touch with Antunez over the weekend and fear he may have been detained again.

Crackdowns on democracy activists in Cuba have actually increased in the lead-up to the embassy openings, according to a report from the Institute for Cuban and Cuban-American Studies at the University of Miami.

Cuban authorities "committed more than 2,000" human rights abuses between April and June of this year alone, the report said, including arbitrary arrests, physical aggression, vandalism, harassment and "acts of repudiation."

In June, Cuban police arrested or cited 563 activists, some locked in police vehicles for hours and others brutally assaulted, according to the report.