The German government has urged American authorities to give German MPs access to key documents in the EU-US trade negotiations known as TTIP.
The request came amid widespread opposition to the confidential talks, which are aimed at creating the world's biggest free trade zone.
Some German government officials, but not MPs, can read documents that reveal the EU and US negotiating positions, at the US embassy in Berlin.
Less sensitive TTIP texts are online.
TTIP stands for Transatlantic Trade and Investment Partnership. EU and US officials hope to complete the wide-ranging talks next year.
Opponents say it is undemocratic, favours big corporations and threatens consumer and worker rights.
An online campaign called Stop TTIP has collected more than three million signatures and handed over a European Citizens' Initiative (ECI), which the European Commission must now examine.
The Commission and many politicians argue that a TTIP deal would bring major benefits for the US and Europe, creating new jobs and business opportunities.
A study by the Centre for Economic Policy Research (CEPR) estimated the potential gains for the EU as up to €119bn (£84bn; $128bn) a year and €95bn for the US.
National politicians in Europe have no automatic right to read the TTIP consolidated texts, which reveal both sides' negotiating positions.
US Congress members can, however, read those documents, as can European Parliament members (MEPs) in a high-security room.
At the US embassy, German government officials have to leave their mobile phones outside the reading room and cannot copy the TTIP texts in there.
The EU Commission and US have "now agreed to give German MPs access to the consolidated texts", the German Economy and Energy Ministry told the BBC.
Earlier the German ambassador to Washington had urged US Trade Representative Michael Froman to grant such access.
A European Commission trade spokesman told the BBC that such access for national parliamentarians "is one of the issues that need to be solved".
"The Americans will have to agree to our approach - we are confident that a solution... can be found very soon.
"All EU governments have full access to all TTIP documents," spokesman Daniel Rosario added.
On Thursday the EU Commission also gave the US a plan for new investment courts to arbitrate in trade disputes. It says the new courts should be transparent and include an appeals process.