Egyptian opposition activists and police have clashed during the final round of parliamentary elections.
The opposition says police are stopping its supporters from voting
One opposition supporter was shot dead and another wounded north of Cairo as police opened fire on voters.
Riot police blocked entry to polling stations in some Muslim Brotherhood and opposition strongholds.
The elections are being seen as a potential watershed for Egypt after the technically-banned Brotherhood made gains in previous rounds.
The violence follows the arrest of hundreds of opposition Islamists.
A spokesman for the country's judges responsible for supervising the elections, Mahmoud al-Houderi, has threatened to pull the judges out if the government prevents people from voting.
"We have witnessed in [some constituencies] the sealing off polling stations to voters by police... Judges monitoring the stations have been prevented from opening them to let in voters," Mr Houderi told the BBC.
Voters resorted to using ladders to get into a polling station in Bosat
An Interior Ministry spokesman, Police General Ibrahim Hamad, said a large security force was deployed to prevent disruption at polls and that voters were welcome.
BBC Cairo correspondent Ian Pannell says the elections were supposed to be a test of the government's commitment to reform, but at best its report card will be mixed.
Although there were important changes to procedures, there have been a number of cases where supporters of the ruling party have relied on illegal tactics to manipulate the vote.
The US had called on Egypt to ensure that people can vote freely and Amnesty International also expressed concern about the violence, intimidation and mass arrests in previous.
More than 10 million Egyptians are eligible to vote in Thursday's third and final round, with 136 of the parliament's 454 seats up for grabs.
The Muslim Brotherhood has already increased its presence in parliament five-fold in two previous rounds of voting, taking it to 76.
The party gets round the ban on its activities by fielding candidates as independents.
Egypt's oldest and largest Islamist organisation
Founded by Hasan al-Banna in 1928
Group has influenced Islamist movements worldwide
Mixes political activism with charity work
Banned from open political activity
Rejects the use of violence and supports democratic principles
Wants to create a state governed by Islamic law
Slogan: "Islam is the Solution"
The brotherhood also said that more than 500 members had been arrested in the governorates where Thursday's election would be fought out, including Daqahliya, Kafr al-Sheikh, Sharqiya, all in the Nile Delta, and Suhaj in the south.
It accused the ruling National Democratic Party (NDP) of President Hosni Mubarak of wanting to thwart its election campaign.
The NDP was already sure of a majority in the new parliament ahead of Thursday's voting.
Monitors said the second round of voting on Saturday was marred by violence between rival political groups, voter intimidation and fraud.
Judges supervising the election have also criticised government forces for failing to intervene when intimidation took place, and questioned the results of the second round.
The ruling NDP has suffered a number of setbacks, but has won 201 seats so far and is still expected to win the majority of seats.
The final results will not be known for another week.
Balance of power
BBC Arab Affairs analyst Magdi Abdelhadi says despite the violence and the widespread allegations of fraud, this election may still prove to be the event that radically alters the Egyptian political landscape.
The Muslim Brotherhood's unprecedented success has altered the balance of power between the government and the opposition.
It has given the brotherhood a legal platform within the Parliament. Under parliamentary immunity rules its newly elected members will be able to challenge and question the ruling NDP's policies without fearing the usual arrests and harassment.