The arrests and a government announcement Monday that President Robert Mugabe had appointed loyalists to several posts were likely to fuel opposition accusations Mugabe is undermining stalled power-sharing negotiations.
Eliah Zembere was among seven Movement for Democratic Change activists police have said they were seeking, alleging they were involved in election violence. The other man, Sure Mudzingwa, was not on the list.
Two uniformed and three plainclothes officers who made the arrests did not say why or where the two were being taken.
Police spokesman Wayne Bvudzijena said he was unaware of Monday's arrests: "It would be illegal for anyone to be arrested while they were proceeding to parliament," he said.
Independent human rights groups have said that President Robert Mugabe's forces were responsible for most of the violence since the opposition won the most seats in March 29 legislative election.
Opposition leader Morgan Tsvangirai beat Mugabe and two other candidates in presidential elections held alongside the legislative balloting, but did not gain the simple majority of votes needed to avoid a runoff. Mugabe and Tsvangirai have entered into power-sharing negotiations.
Opposition spokesman Nelson Chamisa said the Movement for Democratic Change remained determined to take up seats in parliament, which Mugabe was to open Tuesday for the first time since the elections nearly five months ago.
Chamisa charged that the arrests were politically motivated - an attempt by Mugabe's ZANU-PF party to regain control of parliament. ZANU-PF had controlled parliament since independence in 1980 until the March vote.
"ZANU-PF are in a desperate attempt to try and stop or abort our victory," Chamisa said. "It's a struggle. We have to fight it out."
Tsvangirai's party has 100 seats in the 210-seat legislature; Mugabe's party holds 99. A faction that broke away from the opposition has 10 and an independent politician who broke away from Mugabe's party has the remaining seat.
Tsvangirai had criticized the reconvening of parliament given the deadlock in power-sharing talks mediated by South African President Thabo Mbeki.
Leaked documents from the talks show Tsvangirai balked at signing a deal based on an offer making him prime minister with limited powers and answerable to Mugabe, remaining as president.
The documents show the prime minister would be deputy chairman of the Cabinet and the president and the prime minister would need to agree on ministerial posts. With the prime minister reporting regularly to the president, Mugabe's power would be left virtually intact.
On Monday, state media reported that Mugabe had appointed eight governors and three senators, all ZANU-PF loyalists. One of the new senators, Patrick Chinamasa, is a Mugabe hard-liner who lost his parliamentary seat in March and who has led the ZANU-PF team in the power-sharing negotiations.
The opposition has argued that the appointed governor positions should be abolished, saying their only function is to provide power and salaries for Mugabe's cronies.
The political impasse has worsened Zimbabwe's economic meltdown. Official inflation is given as 11 million percent, but independent financial institutions say it is closer to 40 million percent amid acute shortages of food, gasoline, medicine and most basic goods.