Discussions on civil nuclear deal are expected to be high on agenda of the talks that Prime Minister Manmohan Singh will have with US President George W Bush in Germany this week, on the sidelines of the G-8 Summit.Singh will undertake a four-day visit to Berlin from Wednesday to attend the summit that will discuss issues like climate change and trade and investment.Focus has shifted to the meeting between Singh and Bush in the context of civil nuclear deal after negotiators of the two countries were unable to resolve all differences on the proposed "1-2-3 agreement" in the latest round of talks that concluded here yesterday.Singh and Bush are expected to give a political push at the highest level to enable the negotiations on the complex agreement to move forward.The three-day talks between Foreign Secretary Shivshankar Menon and US Under Secretary of State Nicholas Burns could not result in any breakthrough due to persisting differences, particularly on whether or not India should have the right to reprocess spent nuclear fuel.The issue of climate change is also expected to figure prominently in the meeting between Singh and Bush, in the backdrop of the latter's remarks that India, along with China, produces most greenhouse gas emissions.New Delhi has serious objections to being solely blamed for affecting the environment and Singh is expected to convey to Bush that greenhouse gas emissions in India were linked to its energy security, a senior official said here.