Can't execute a python command (gdal2tiles.py) from PHP

Question

I am trying to execute the following command from PHP (run on ubuntu)

"gdal2tiles.py" -p raster -z 0-6 -w none '/opt/lampp/htdocs/attachments/pt.png'

Running this command into the terminal works fine, but from php it gives me the following error

python: /opt/lampp/lib/libz.so.1: no version information available (required by python)
Traceback (most recent call last):
  File "/usr/bin/gdal2tiles.py", line 38, in <module>
    from osgeo import gdal
  File "/usr/lib/python2.7/dist-packages/osgeo/__init__.py", line 21, in <module>
    _gdal = swig_import_helper()
  File "/usr/lib/python2.7/dist-packages/osgeo/__init__.py", line 17, in swig_import_helper
    _mod = imp.load_module('_gdal', fp, pathname, description)
ImportError: /usr/lib/i386-linux-gnu/libkrb5.so.26: undefined symbol: sqlite3_open_v2
Error in sys.excepthook:
Traceback (most recent call last):
  File "/usr/lib/python2.7/dist-packages/apport_python_hook.py", line 66, in apport_excepthook
    from apport.fileutils import likely_packaged, get_recent_crashes
  File "/usr/lib/python2.7/dist-packages/apport/__init__.py", line 1, in <module>
    from apport.report import Report
  File "/usr/lib/python2.7/dist-packages/apport/report.py", line 20, in <module>
    import apport.fileutils
  File "/usr/lib/python2.7/dist-packages/apport/fileutils.py", line 22, in <module>
    from apport.packaging_impl import impl as packaging
  File "/usr/lib/python2.7/dist-packages/apport/packaging_impl.py", line 20, in <module>
    import apt
  File "/usr/lib/python2.7/dist-packages/apt/__init__.py", line 21, in <module>
    import apt_pkg
ImportError: /usr/lib/i386-linux-gnu/libapt-pkg.so.4.12: undefined symbol: gzseek64

Original exception was:
Traceback (most recent call last):
  File "/usr/bin/gdal2tiles.py", line 38, in <module>
    from osgeo import gdal
  File "/usr/lib/python2.7/dist-packages/osgeo/__init__.py", line 21, in <module>
    _gdal = swig_import_helper()
  File "/usr/lib/python2.7/dist-packages/osgeo/__init__.py", line 17, in swig_import_helper
    _mod = imp.load_module('_gdal', fp, pathname, description)
ImportError: /usr/lib/i386-linux-gnu/libkrb5.so.26: undefined symbol: sqlite3_open_v2

Can anybody help?