Filter Paired-End Sam File For Xt:A:U

Dear all,

I have a sam file (BWA output, paired-end reads). I would like to retain only reads which are "properly paired". This I would do by:

samtools view -f 0x002 file.sam > file_filtered.sam

Additionally I would like to retain only those pairs of reads where both reads have the XT:A:U tag. It is important to me that after the filterting step I still have the pairs together (so read1, read2, read1, read2, ...).

Any ideas how to do so?

Thanks for any help! Stefanie