document: It is understood that the Indian owners of the plant fear that the current UK political uncertainty could derail efforts linked to the planned sale.
  Concerns centre on proposed changes to the pension scheme which are crucial to securing the future of the business.
  The government says its consultation on the scheme is closed, and it will respond in due course.
  Tata announced in March that it was considering selling its UK steel business, putting 11,000 jobs at risk.
  But buyers are reluctant to take on the huge steelworkers' pension scheme, which has 130,000 members. Including spouses and children, hundreds of thousands of people depend upon it.
  The scheme also has a deficit of about Â£700m.
  In May, the business secretary Sajid Javid launched a consultation outlining options to resolve the pensions issue.
  But it is understood that Tata now has concerns that the political uncertainty surrounding the Tory leadership battle could derail the process.
  "It's clearly an incredibly busy time in UK politics," a source close to the company said.
  "Nevertheless, the company still hopes that the hundreds of thousands of people in Britain who are dependent on a steel pension will not be left worse off by the current political leadership uncertainties."
  The consultation on Tata's pension scheme is being handled by the Department of Work and Pensions.
  On Wednesday the Work and Pensions Secretary Stephen Crabb announced his intention to run for the leadership of the Conservative Party.
  He is being backed by Sajid Javid, who hopes to become chancellor if Mr Crabb wins. Mr Javid has led efforts to resolve the crisis in the steel industry which has intensified under his watch.
  That's led to concerns that the leadership race could take priority over efforts to resolve the pensions issue.
  The consultation on the scheme closed on 23 June, with a government response due four weeks later, just before the summer parliamentary recess.
  The Tata Steel pension consultation included a plan to base the scheme's annual increase on the CPI measure of inflation rather than RPI, a move expected to save billions of pounds.
  While reducing payouts, the plan would leave most pensions holders either better off or no worse off compared with entering the Pension Protection Fund - the industry lifeboat for pension schemes that go under.
  But the plans have been criticised for setting a precedent that could lead other employers to attempt to dilute their pensions promises.
  A DWP spokesman said: "Our consultation into the British Steel Pensions Scheme has now closed. We have received over 5,000 responses and will respond in due course."
  You can follow John at @JohnMoylanBBC
summary: Fresh concerns have emerged over the future of Tata Steel's UK assets, which include the huge Port Talbot works.