The EU has taken a step towards common rules for cracking down on those who sexually abuse children and post images of the abuse on the internet.
A committee of Euro MPs backed an EU draft directive calling for child abuse images to be removed at source.
Where removal is impossible - for example, because web pages are hosted outside the EU - then the abuse images may be blocked by national authorities.
MEPs aim to adopt the new rules later this year, after further negotiations.
MEPs insisted that any moves to block access to images on the web must be accompanied by "transparent procedures and provide adequate safeguards" so that "the restriction is limited to what is necessary and proportionate".
The safeguards would include informing users of the reason for the block and informing content providers and users of their right to appeal.
The original proposal from the European Commission called for mandatory blocking of child abuse websites in the 27-nation EU.
But in some cases, such blocking action could be seen as a violation of fundamental rights.
The amended text was adopted overwhelmingly by the European Parliament's Civil Liberties Committee on Monday.
The Commission recommended both the removal of child abuse content at source and blocking as a complementary tool, admitting that blocking was not always effective.
Internet blocking exists already in the UK, Denmark, Italy, Finland and Sweden.
"The experience of these countries shows that hundreds, or even thousands, of attempts to access child pornography sites are blocked every day," EU Home Affairs Commissioner Cecilia Malmstroem said last year.
An alliance of European child protection groups, including the UK's NSPCC, called the new directive an "important opportunity" to improve EU legislation aimed at preventing sexual crimes against children.
Making grooming a crime
The directive would make the sexual grooming of children via the internet a crime across the EU.
It seeks to make undercover police operations a "possibility... in national legislation" to target paedophile rings that prove particularly difficult for the authorities to access.
A range of measures would also boost legal support for child victims, as well as protections such as vetting of adults who work with children.
Offenders would face prison terms ranging from two years to more than 10 years, depending on the gravity of the crime.
In addition, EU states plan to step up partnerships with Russia, the US and other non-EU countries to combat child abuse on the internet.
MEPs will now discuss the directive with EU governments, with the aim of reaching a deal within months. Once adopted, the directive will have to be incorporated into national law EU-wide within two years.