File: The International Cricket Council distanced itself from the protests.
BIRMINGHAM - Tournament chiefs said they were working with authorities to establish a no-fly zone over Lord's for the World Cup final after political banners were flown in Birmingham during Thursday's semi-final between England and Australia.
The signs read "World must speak up for Balochistan" and "Help end disappearances in Pakistan".
It follows similar incidents earlier in the tournament in England and Wales, with the International Cricket Council distancing itself from the protests.
"We do not condone any sort of political messages at the ICC Men's Cricket World Cup," the ICC said in a statement.
"We have worked with local police forces around the country throughout the tournament to prevent the World Cup being used as a platform for political protests.
"So we are incredibly disappointed these flights continue to take place. We are working very closely with the relevant agencies to make sure there is an air exclusion zone in place for manned and unmanned flights during the (Sunday's) final at Lord's."
The sky above Old Trafford was declared a "no-fly zone" for the first semi-final between India and New Zealand this week after a light aircraft flew banners over Headingley during India's match against Sri Lanka reading "#Justice for Kashmir" and "India stop genocide & free Kashmir".
A "Justice for Balochistan" banner was flown over Headingley during the Pakistan-Afghanistan match last month, where police had to intervene following violent clashes between fans.
Balochistan, Pakistan's largest and poorest province, which borders Afghanistan and Iran, is rife with Islamist, separatist and sectarian insurgencies.
The Pakistani military has been waging war on militants there since 2004, and security forces are frequently targeted.
Police made two arrests at the first semi-final on Tuesday but both men were released without charge.
Fans, apparently Sikh separatists, wore T-shirts and held banners demanding a referendum on an independent homeland to be carved out of India.