* FTSE 100 up 0.3%, FTSE 250 up 0.4%
* Miners gain as nickel prices hit record high
* Positive U.S.-China trade signals buoy sentiment
* AIM-listed Shoe Zone tanks after warning on results (Adds news items, analyst comments, updates share prices)
Aug 30 (Reuters) - London's FTSE 100 rose on Friday, lifted by gains in miners as nickel hit an all-time high, with sentiment supported by signs of a resumption of U.S.-China trade talks.
The main index added 0.3%, putting it on track to post its first weekly gains in five. The mid-cap FTSE 250 gained 0.4% by 0738 GMT.
Heavyweight miners such as Rio Tinto and BHP provided the biggest boost to the blue-chip index as a waste spill at a nickel plant in Papua New Guinea sparked supply fears.
Most other constituent sectors on the FTSE 100 were also higher after Washington and Beijing signaled overnight that they would resume talks to try and end their protracted trade war.
"The more measured tone in deciding to focus on next month's meeting to discuss removing the extra duties has seen some optimism start to creep back in," said CMC Markets analyst Michael Hewson.
Worries that the trade war would escalate have stoked fears of a global recession in recent weeks and put the FTSE blue-chip index on course for its sharpest monthly fall in four years.
"All-in-all, it emphasizes once again that the U.S.-China trade dispute and/or its resolution remains the only game in town for investors globally," said Jeffrey Halley, senior market analyst, Asia Pacific at Oanda.
The sterling remained subdued as lawmakers scrambled to find a solution to the chaotic Brexit process, pushing up exporter stocks such as Diageo and Unilever nearly 1%.
The more domestically-focussed FTSE 250, which has broken ranks with the local currency in recent months, gained, supported by a 6% surge in building materials distributor Grafton after its first-half results.
Shares of blue-chip IT group Micro Focus and mid-cap consumer credit provider Amigo Holdings clawed back some losses from the previous session's steep falls. Micro Focus rose 5%, while Amigo advanced 6.5%.
Among smaller stocks, footwear retailer Shoe Zone plunged 30.7% to an all-time low after warning annual results would be below expectations.
Premier Foods rose 2.5% after the OXO cube maker appointed a permanent chief executive officer and a new chairman, filling a void left by a string of top management departures earlier this year. (Reporting by Shashwat Awasthi in Bengaluru; Editing by Sriraj Kalluvila)